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GENERAL CHEESE MAKING BOARDS (Specific Cheese Making in Boards above) => EQUIPMENT - Forming Cheese => Topic started by: tal_d1 on October 22, 2012, 05:28:26 AM

Title: Commercial Gouda press
Post by: tal_d1 on October 22, 2012, 05:28:26 AM
I saw a movie making Commercial Gouda.
The press is done with hydraulic machine. they
put about 10 molds of cheese on one other and press
them together. So the mold at the bottom has about 9
cheese on it and the one at the top has no mold on it so the weight of the press
applied on the molds has a big different. Is their a big
different between the cheeses ?
Title: Re: Commercial Gouda press
Post by: bbracken677 on October 22, 2012, 06:04:22 AM
If I am not mistaken, I believe they are rotated positionally so it all works out.
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on October 28, 2012, 10:17:37 PM
I saw a movie making Commercial Gouda.
The press is done with hydraulic machine. they
put about 10 molds of cheese on one other and press
them together. So the mold at the bottom has about 9
cheese on it and the one at the top has no mold on it so the weight of the press
applied on the molds has a big different. Is their a big
different between the cheeses ?

The only difference between the cheeses is due to gravity which I would think is negligible here given the magnitude of the pressure applied to goudas. I doubt there is much of a difference at all unless you are stacking a ton of cheeses on top of one another. The gravitational force would have to be approximately of the same order as the pressing force. I would expect it is not within an order of magnitude, maybe two. IE, you press a 2 lb gouda with about 50 or more lbs given about a 4-5 in mold, they are off by an order of magnitude or about a factor of 10. Now hypothetically, if you stacked 10 of them on top of each other and kept the pressing force at 50 lbs, you would have a total of 20 additional lbs acting on the bottom cheese. 20 is sufficiently close to the pressing force of 50 lbs for it to become significant. 
Title: Re: Commercial Gouda press
Post by: bbracken677 on October 28, 2012, 10:25:12 PM
I saw a press that pressed 10 or so molds at one time, but instead of being stacked vertically, they were pressed horizontally...as a result I would think there would be a relatively small difference in pressure between the middle molds and the end ones. It could possibly be significant enough to warrant a rotation.
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on October 28, 2012, 10:31:23 PM
I saw a press that pressed 10 or so molds at one time, but instead of being stacked vertically, they were pressed horizontally...as a result I would think there would be a relatively small difference in pressure between the middle molds and the end ones. It could possibly be significant enough to warrant a rotation.

Actually, in that case the difference would be zero. The force on them would be identical due to Newton's third law of physics. Kind of a weird truth.
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on October 28, 2012, 10:35:08 PM
I saw a press that pressed 10 or so molds at one time, but instead of being stacked vertically, they were pressed horizontally...as a result I would think there would be a relatively small difference in pressure between the middle molds and the end ones. It could possibly be significant enough to warrant a rotation.

Actually, in that case the difference would be zero. The force on them would be identical due to Newton's third law of physics. Kind of a weird truth.

Or if you really want to be a nerd about it. The gravitational component of the net force vector is orthogonal to the pressing (normal) force component and thus contributes nothing to the pressure on each individual mold. (Newton's third law effectively ensures the pressing force is uniform on each mold).
Title: Re: Commercial Gouda press
Post by: bbracken677 on October 28, 2012, 10:39:36 PM

Actually, in that case the difference would be zero. The force on them would be identical due to Newton's third law of physics. Kind of a weird truth.

While I do understand what you said, i do believe that isn't entirely correct. There is resistance, and friction involved. The transfer of force from one to the next to the next etc would, I believe, diminish somewhat in the middle ones. However, the difference may not be enough to be of any significance.
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on October 28, 2012, 11:08:07 PM

Actually, in that case the difference would be zero. The force on them would be identical due to Newton's third law of physics. Kind of a weird truth.

While I do understand what you said, i do believe that isn't entirely correct. There is resistance, and friction involved. The transfer of force from one to the next to the next etc would, I believe, diminish somewhat in the middle ones. However, the difference may not be enough to be of any significance.

Sure, but assuming your molds are properly constructed (and thus your followers slide properly), friction should be negligible, particularly since in this case friction is a function of gravity which is very small compared with the pressing force (again, assuming your molds are not made of sandpaper).

Its all about magnitudes. The magnitude of the pressing force is so dang high compared to everything else that is demolishes any other forces which might be contributing here. Is there a friction component? Undoubtedly. But factoring it in would be a matter of splitting hairs. Physics is never about absolutes (very very rarely at least), it is all about making dang good approximations by ignoring the details which approach pointlessness (IE details that would never in a million years effect the outcome of the calculations involved).
Title: Re: Commercial Gouda press
Post by: smolt1 on October 28, 2012, 11:47:16 PM
I wonder if Newton made any cheese.
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on October 29, 2012, 01:07:38 AM
I wonder if Newton made any cheese.

Don't know. Would not be surprised though, Newton reportedly had farming in his background.
Title: Re: Commercial Gouda press
Post by: bbracken677 on October 29, 2012, 09:49:05 AM
Not friction with the follower (other than very little, since there would be some contact) but rather the contents of the mold...you are applying pressure to a material that becomes compressed. Consider a series of springs and you apply force to both ends of the series...you would see more compression at the ends than you would in the center. 
More than likely the difference (as in with pressing cheeses) is insignificant.
Title: Re: Commercial Gouda press
Post by: smolt1 on October 29, 2012, 11:04:41 AM
Try a mental experiment.
You have 5 springs and a scale. Each spring weighs 1 lb.
Stack the springs 5 high on the scale. What does the scale read?
Stack the springs 4 high on the scale. What does the scale read?
Now add a 1 lb weight on top of the 4 th spring. What does the scale read?
Each spring is independent and does not know if it is a spring or a weight on top of it.
Title: Re: Commercial Gouda press
Post by: Mike Richards on October 29, 2012, 11:12:32 AM
You guys are pretty funny.  You should come attend my Statics and Strength of Materials class.
Title: Re: Commercial Gouda press
Post by: bbracken677 on October 29, 2012, 12:30:32 PM
ahh...Colorado...don't think my attendance would be up to par  :)

So...what's your take on the question at hand?

I think the weight of the springs problem is a subtly different issue. For one, with the molds (springs) being pressed horizontally, weight (gravity) does not play a part in the answer.  On the other hand, I do see the point you are making.
If you had a line of molds (horizontally) that approached infinity, and applied pressure to one end, would the other end experience any pressure at all?
Title: Re: Commercial Gouda press
Post by: Mike Richards on October 29, 2012, 12:49:45 PM
Something has always got to be pushing back.  If I put 10 lbs of load on one side of something, if it's in equilibrium (not moving), then something is pushing back with 10 lbs.

In a vertical cheese press system, the load carried by the bottom cheese (assuming no load is transfer to the molds--which a good design would try to ensure) would be equal to the load applied to the top cheese plus the weight of each of the cheeses and molds on top. 

In a horizontal system, you can introduce a little bit of complexity in the analysis if the molds are resting on something, but if they are suspended between the load applying end (a piston of some sort, perhaps) and the "base" such that those are the only two points in contact with the stack of cheeses, each cheese will experience the same force.

So, in the case of an infinitely long, horizontal stack of molds, if the molds are only touching one another, they will each be carrying the same load.  If they are resting on the ground, the friction between each mold and the ground will lessen the load the next cheese carries until there is no longer any load applied to the cheeses.  Example: 10 lbs of load is applied, cheese 1 experiences 10 lbs, but 1 lb of the reaction is provided not by the next cheese in line, but by friction with the ground.  Cheese 2 expereiences 9 lbs, Cheese 3 8 lbs, etc.
Title: Re: Commercial Gouda press
Post by: bbracken677 on October 29, 2012, 01:45:54 PM
So in other words, you are saying that the compression of the cheeses being pressed in the near infinite line of molds would all be experiencing the same pressure?

Newton's first law, an object at rest tends to remain at rest...so when one applies pressure at one end of the line of cheese/molds regardless of the compression involved with the cheeses themselves, this pressure is distributed evenly throughout the near infinite line of molds/cheeses?  Mind boggling  lol
Title: Re: Commercial Gouda press
Post by: Mike Richards on October 29, 2012, 02:07:23 PM
Yep--and now I might have to make up a question like this to put on an exam...
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on October 29, 2012, 04:37:22 PM
Something has always got to be pushing back.  If I put 10 lbs of load on one side of something, if it's in equilibrium (not moving), then something is pushing back with 10 lbs.

In a vertical cheese press system, the load carried by the bottom cheese (assuming no load is transfer to the molds--which a good design would try to ensure) would be equal to the load applied to the top cheese plus the weight of each of the cheeses and molds on top. 

In a horizontal system, you can introduce a little bit of complexity in the analysis if the molds are resting on something, but if they are suspended between the load applying end (a piston of some sort, perhaps) and the "base" such that those are the only two points in contact with the stack of cheeses, each cheese will experience the same force.

So, in the case of an infinitely long, horizontal stack of molds, if the molds are only touching one another, they will each be carrying the same load.  If they are resting on the ground, the friction between each mold and the ground will lessen the load the next cheese carries until there is no longer any load applied to the cheeses.  Example: 10 lbs of load is applied, cheese 1 experiences 10 lbs, but 1 lb of the reaction is provided not by the next cheese in line, but by friction with the ground.  Cheese 2 expereiences 9 lbs, Cheese 3 8 lbs, etc.

Naturally though, the magnitude of the friction involved is highly dependent on the material the molds are resting on. If you have a very smooth surface, perhaps even lubricated, the friction involved starts to approach very small numbers. Also, if they are resting on something like two horizontal bars, two or three points of contact, that will dramatically reduce the friction involved. When I was thinking about this last night, I assumed the "chain" was resting on something very smooth so no weird gravitational effects would lead to tensions or bending of the chain. Personally, I have don't like hyperbolic trig functions (wink at Mike). I also assumed that since this discussion was about commercial presses, likely the cheeses involved were larger and thus involve much greater pressing forces (or load as you call it). In your case, lets assume each cheese assumes a friction equivalent to 1 lb. Lets suppose we are working with 7in diameter molds. Then the cross sectional surface area is about 38.34 in^2. If we want 4 PSI, then that means our piston must apply 153.37 lbs of force. Lets call it 160.So the first mold feels 160 lbs of force, the second 159, on to the nth cheese which feels 160 - (n-1). This means for 10 molds, the last cheese experiences 151 lbs. This is a difference of 9 lbs which is a percentage difference of 9/160 = 5.6%. Personally, I am not inclined to worry about consistency issues there. Of course I have made assumptions here, put into practice other variables could come into play.

I am kind of tempted to code up a model now and run some experiments... cheese is more fun when you geek out on it :p

Mike, two comments:
1) You name seems vaugely familiar to me... You into any other hobbies or things where you use your name (if you don't mind my asking)
2) What field are you in? Some flavor of engineering I assume?
Title: Re: Commercial Gouda press
Post by: Mike Richards on October 29, 2012, 05:28:14 PM
I agree that the loss in load (and thus pressure) would be negligable in a horizontal press system, though it could be significant in a vertical system depending on the pressure needed, size of the wheels, and height of the stack.

It's almost a curse that my name is shared by many, many people.  The most famous of us is Michael Richards, Kramer, from Seinfeld.  Any of these might also be the one you're thinking of http://en.wikipedia.org/wiki/Mike_Richards_(disambiguation) (http://en.wikipedia.org/wiki/Mike_Richards_(disambiguation)).

I once participated in online apologetics, using the name Mike Richards, but have, to the delight of my wife, recovered from that addiction...

I've got a BS in Mechanical Engineering and an MS in Nuclear Engineering.  I currently teach a course in Statics and Strength of Materials, should teach a first semester physics class next semester, and will be joining the Thermal Fluid Science team in the near future teaching Thermodynamics, Fluids, Heat Transfer, etc...(though I'll need to do a little dusting up on those topics before I get in front of a class).

What about you?
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on October 29, 2012, 05:47:58 PM
Oh come on, tell us the truth, you are Krammer! (Just kidding)

B.S./M.S. Mathematics, Physics minor. I work as a software engineer though. When I was studying Physics, most of my elective upper division work was in particle physics.

Apologetics huh? My cousin used to be into Christian Apologetics. I think he got frustrated and quit though, I have so say that for someone with no formal training in logic/philosophy or debate many of his arguments were pretty dang clever! I like philosophy a lot but I am more into logic and epistemology. Metaphysics sometimes makes its way in but is not really a primary interest.
Title: Re: Commercial Gouda press
Post by: bbracken677 on October 30, 2012, 09:15:37 AM
Something has always got to be pushing back.  If I put 10 lbs of load on one side of something, if it's in equilibrium (not moving), then something is pushing back with 10 lbs.


So, in the case of an infinitely long, horizontal stack of molds, if the molds are only touching one another, they will each be carrying the same load.  If they are resting on the ground, the friction between each mold and the ground will lessen the load the next cheese carries until there is no longer any load applied to the cheeses.  Example: 10 lbs of load is applied, cheese 1 experiences 10 lbs, but 1 lb of the reaction is provided not by the next cheese in line, but by friction with the ground.  Cheese 2 expereiences 9 lbs, Cheese 3 8 lbs, etc.

Naturally though, the magnitude of the friction involved is highly dependent on the material the molds are resting on. If you have a very smooth surface, perhaps even lubricated, the friction involved starts to approach very small numbers. Also, if they are resting on something like two horizontal bars, two or three points of contact, that will dramatically reduce the friction involved. When I was thinking about this last night, I assumed the "chain" was resting on something very smooth so no weird gravitational effects would lead to tensions or bending of the chain. Personally, I have don't like hyperbolic trig functions (wink at Mike). I also assumed that since this discussion was about commercial presses, likely the cheeses involved were larger and thus involve much greater pressing forces (or load as you call it). In your case, lets assume each cheese assumes a friction equivalent to 1 lb. Lets suppose we are working with 7in diameter molds. Then the cross sectional surface area is about 38.34 in^2. If we want 4 PSI, then that means our piston must apply 153.37 lbs of force. Lets call it 160.So the first mold feels 160 lbs of force, the second 159, on to the nth cheese which feels 160 - (n-1). This means for 10 molds, the last cheese experiences 151 lbs. This is a difference of 9 lbs which is a percentage difference of 9/160 = 5.6%. Personally, I am not inclined to worry about consistency issues there. Of course I have made assumptions here, put into practice other variables could come into play.

I am kind of tempted to code up a model now and run some experiments... cheese is more fun when you geek out on it :p



Actually...what is the byproduct of compression? Heat...
Heat = energy
As you would add pressure, compressing the cheeses, a small amount of heat loss would result from the compression of each cheese. Long before you reached anything approaching infinity you would be left with something approaching zero pressure and zero compression being applied to the cheese.

The answer to the question related to a chain of cheese molds approaching infinity being pressed, what is the pressure being applied to the last forms in the chain is: Zero

Same thing applies to a series of springs...compression generates heat...heat equals loss of energy...
Title: Re: Commercial Gouda press
Post by: smolt1 on October 30, 2012, 11:23:17 AM
Energy is the ability to do work, and work requires movement ( W=FxX ). Once a static point is reached no more work is done. So once movement has stopped I think that only the reactive force of (static) friction affects the force pushing  on each of the horizontal molds .
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on October 30, 2012, 11:35:09 AM
Energy is the ability to do work, and work requires movement ( W=FxX ). Once a static point is reached no more work is done. So once movement has stopped I think that only the reactive force of (static) friction affects the force pushing  on each of the horizontal molds .

Si senior! Difficult to talk about dynamics when the system is not acting dynamically ;)
Title: Re: Commercial Gouda press
Post by: Mike Richards on October 30, 2012, 09:26:40 PM
I suppose if we include dynamic response, and drop the rigid body assumption (allow the cheeses to compress), then in an infinitely long set of cheeses, the "last" cheese would never feel the force applied to the first cheese.  This, however, is primarily because in an infinitely long set of cheeses, the last cheese is infinitely far away and the force would simply never get to it.  Additionally the mass of the system would be infinite, and what we think of as the inertia of the mass would provide the reaction force keeping the entire system in equilibrium even though there is no real reaction at the other "end" of the stack.  What is more interesting, to me, is that in this same scenario, putting a small force on the "stack" of cheeses would squish the entire stack an infinite amount.  I once pointed out in a class that I could make a beam of steel stretch more than 1 foot with my bare hands.  Of course, the beam would have to be something like 2,000 miles long...but still, I'm like superman!  :D

In a more realistic case, though, with less than an infinite number of cheeses, each individual cheese (in a horizontal press) needs to experience the same force on the front (top) of the cheese as it does on the back (bottom) of the cheese or it would be accelerating.  I suppose that since the cheeses are compressing, the center of mass of the cheese-system is in fact moving away from the piston and towards the "base".  Since this is true, and since the speed with which it is moving is not constant, it must be accelerating (technically, not necessarily going faster), which means the net force on the system must be non-zero.  If the net force on the system is non-zero, then the net force on each individual cheese is also non-zero.  Those cheeses near the piston are accelerating more than those near the base (think of the distance they each travel).  Therefore, the cheeses are experiencing different forces and thus different pressures.

Once the cheeses stop compressing, the center of mass is no longer moving, and the net force across the entire system and within each cheese is zero, so they are all experiencing the same force and thus the same pressure.  I guess, then, that everyone is right, depending on what part of the cheese pressing they were considering.  Some might argued that cheeses are always compressing while in the press--I don't know if that's true, but I doubt it.  It seems to me that they get to a point where they no longer compress under a given load.

And now you can agree with my students that I talk too much...and give details they don't really want: "Just teach us what we need to know for the test."
Title: Re: Commercial Gouda press
Post by: smolt1 on October 30, 2012, 11:00:04 PM
 "Also, if they are resting on something like two horizontal bars, two or three points of contact, that will dramatically reduce the friction involved."

As long as we have traveled to Nerd city, let me ask if it is not true that the static friction is only dependent on the normal force ( not the area of contact).
Title: Re: Commercial Gouda press
Post by: Mike Richards on October 30, 2012, 11:24:40 PM
That is correct--contact area doesn't affect friction, it's simply the product of the normal force and the coefficient of friction (either static or kinetic).  For most of us, this comes as counter-intuitive and usually requires us to just hit the "I believe" button and move on (this is one of those topics that I have never internalized as true, and just continually hit the "I believe" button).  There are certain circumstances where surface area does matter (like when things are sticky...) to resistance forces (I'm not sure that we'd really call those friction, though).

Thanks for visiting Nerd city, by the way.  I kind of figured this forum was a suburb of Nerd City--I mean, what kind of people really make cheese, anyway?  ;)
Title: Re: Commercial Gouda press
Post by: smolt1 on October 31, 2012, 01:09:45 AM
If you think of friction as if it is caused by the pressure between two surfaces then it becomes more intuitive. So then a contact area of 30 square inches is 30 times the area of a 1 square inch area , but the pressure is 1/30th so the friction force is the same for both.
Title: Re: Commercial Gouda press
Post by: Schnecken Slayer on October 31, 2012, 04:06:33 AM
This is one thing that I have been considering / confused by in my brief foray into cheesemaking.

They say press at 10 pounds for example.

However if you press a 10cm cheese at 10 pounds it is different to pressing a 20 cm cheese at 10 pounds. As far as I can see.

It gets back to PSI, pounds per square inch.

Maybe I should do the experiment?
Title: Re: Commercial Gouda press
Post by: Alpkäserei on October 31, 2012, 11:05:14 AM
I tried to skim all of the pertinent information out, but maybe I missed this. I don't think it has come up though.

Another factor we have is the slack present in each cheese. During the first several pressings, each of the cheeses is actually absorbing some of the energy being put into it. Otherwise the pressing would be doing nothing. The cheese is not merely a vessel through which the energy passes, the object of the pressing is to change the cheese, and this requires a certain amount of energy to accomplish. So some of our weight, instead of shooting straight through to the bottom, gets distracted in our cheese. This of course diminishes each time we press the cheese. But in a heavy press stack, I can notice more wehy fleeing from the top cheese than from the bottom (taking some of our energy with it)

A certain amount of the pressing weight is being used by each cheese to pack and rearrange the curd structure. Having pressed stacked cheeses before, experience tells me that position does make a big difference, and rotation is very important to getting consistent results.

You do need to factor your pressing weight for the size of your cheese. Some say PSI, I prefer to factor by mass. Because what if you factor your weight by the surface area of a cheese, but one is tall and the other is thin? The tall cheese will not press as well under the same weight as the thin one. Yes, a quick look at static physics should tell us that this shouldn't matter. But this assumes we are pressing a consistent gel, which we are not. We are pressing a large mass that has holes in it, pockets of liquid, and maybe even curd in various stages of dryness. factoring by weight accounts for the fact that a bigger mass of cheese is going to have more curd space to remove than a smaller one of the same diameter. It will either take more force (i.e. weight) or more time to press the bigger cheese with the same diameter as a smaller one effectively.

I factor pressing weight by the weight of the cheese to be pressed, and multiply by 8.
Title: Re: Commercial Gouda press
Post by: smolt1 on October 31, 2012, 11:44:17 AM
The discussion of the physics of the friction of the multiple horizontal molds has almost nothing to do with actual process of cheese making. It is only some physics nerds having fun. In cheese making , it's experience,  experience,experience.
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on October 31, 2012, 11:56:49 AM
Thanks for visiting Nerd city, by the way.  I kind of figured this forum was a suburb of Nerd City--I mean, what kind of people really make cheese, anyway?  ;)

Amen my friend!
Title: Re: Commercial Gouda press
Post by: bbracken677 on November 01, 2012, 09:03:01 AM
The discussion of the physics of the friction of the multiple horizontal molds has almost nothing to do with actual process of cheese making. It is only some physics nerds having fun. In cheese making , it's experience,  experience,experience.

haha so true! 
But in reality, I believe that the compression, even in the absence of friction, would have a significant affect on loss of pressure the longer the chain is. Compression results in heat, which is a conversion of energy in the system from pressure to heat, resulting in an eventual pressure of zero at some point in the chain.
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on November 01, 2012, 10:39:47 AM
The discussion of the physics of the friction of the multiple horizontal molds has almost nothing to do with actual process of cheese making. It is only some physics nerds having fun. In cheese making , it's experience,  experience,experience.

haha so true! 
But in reality, I believe that the compression, even in the absence of friction, would have a significant affect on loss of pressure the longer the chain is. Compression results in heat, which is a conversion of energy in the system from pressure to heat, resulting in an eventual pressure of zero at some point in the chain.

Alright alright.... I'm gonna go all nerd this weekend and try to do the actual computations (although thermal is not a strong point of mine, I was more of a nuclear/particle guy...). Oh, and I actually have a cheesemake scheduled this weekend- ordered some fresh B. linens, I will make a point of doing these comps while the curds are cookin! For added nerdiness, I will use a Dungeons and Drangons Monstrous Manual as a hard back surface to do the writting on and stare at a picture of the starship enterprise blowing up an army of ceylons while Gandolf charges in riding on the back of that dragon/dog creature from The Neverending story. All this while kicking back in a gamers chain sitting on top of a big pile of Magic the Gathering cards (Too bad I do not wear glasses because that would be nerd icing on the cake!). I'll be sure to drink a YooHoo while I am at it.

In all seriousness, I am intrigued now, perhaps I will do those comps and then try to code up a model simulation in MatLab or something. Lets get to the bottom of this Scooby Doo mystery!
Title: Re: Commercial Gouda press
Post by: bbracken677 on November 01, 2012, 11:54:22 AM
You left out farming in World of Warcraft!  lol 

I used to be a WoW head...
Title: Re: Commercial Gouda press
Post by: Mike Richards on November 01, 2012, 08:24:13 PM
I wear glasses... :-[
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on November 01, 2012, 09:42:40 PM
I wear glasses... :-[


(http://1.bp.blogspot.com/-38Or80_CcWg/T2GKmR2YIBI/AAAAAAAAJwE/K2jN2vtuex8/s1600/618px-JeanLucPicardFacepalm.jpg)

Doh!
Well, I never meant it in a bad way.
Title: Re: Commercial Gouda press
Post by: Mike Richards on November 01, 2012, 09:53:46 PM
It's okay--because I never played magic...though I do watch star trek frequently.

It will be interesting to see what the detailed numbers say, but I'm certain the difference in pressure across a realistic (are we talking about the realistic case now or the imaginary, crazy long case?) set of cheeses will be relatively small.  Here's a back of the envelope analysis.

The energy involved shouldn't be enormous.  The work, W, being done by the press on the cheeses is equal to the force, F, being applied times the distance, d, the "piston" travels through, or, in nerd: W =Fd (this is the equation for constant F across the entire length of d, which we will assume for simplicity).  If we want 6 psi across a 6 in wheel, we'll need ~ 170 lbs ( 3in^2 * pi * 6 psi).  Let's say our molds hold 9 inches of curd that will be compressed down to 3 inches (that seems like a lot to me--so our number should be higher than we find in reality).  That means for every cheese we have in the line, we'll compress 6 inches.  So, if we have 10 cheese, we expect to compress 5 feet (10 * 6 in).  Using our formula for work, we will do W = 5 ft * 170 lbs = 850 ft lbs of work.  I don't do well with ft lbs of work, so let's convert those to joules.  There are 1.36 joules in a ft lb, so we have 1156 joules of work being done.  While not all of this work will go into heat, let's pretend it does and see how much heat that is.  This amount of energy would raise 1 liter of water 0.28 degrees C--so not very much energy.

Considering again the relative motion of the cheeses in the stack, the first one being pressed moving the fastest, and the last one in the stack not really moving at all, the difference they experience in pressure will be directly related to the difference in force across the cheese.  This force will be easiest to determine if we could measure the acceleration of the cheeses.  Again, the first cheese will experience the most significant difference in pressure since it moves the fastest (thus, accelerates the most).  However, I don't have access to an industrial, horizontal cheese press (it's on the wish list  ;)).  Let's be a little crazy and pretend that the cheese accelerates at 1/10 the acceleration of gravity.  Just to help think about this, if something accelerates at that rate for 1 second, it will be traveling at a velocity = acceleration * time = 1 m/s^2 (really 0.981 m/s^2...) * 1 second = 1 m/s ~ 2.2 miles/hour.  People walk at about 3 miles/hour, so this is slightly slower than you walk, and, I presume, really stinking fast for a press to be pressing cheese.  Now, let's assume the cheeses we are pressing are 2 kg each.  The difference in force across this cheese, then, if F = ma = 2 kg * 1 m/s^2 = 2 Newtons.  In fact, in the very fist instance, there is no reaction from the second cheese on the first cheese, so the 2 Newton "difference" is really all the force that the press is providing.  However, as soon as the first cheese "engages" the second cheese, the second cheese provides a reaction, and the press must provide more than 2 Newtons.  A similar phenomenon happens for each cheese in the stack--the second cheese has an instantaneous acceleration before being engaged by the third cheese, and so on.  In this first instant, we find the most significant difference in pressures the cheeses experience.  Since the last cheese is engaged last, it experiences 0 force, and thus 0 pressure while all the other cheeses are being pressed. Once all the cheeses are engaged, the force provided by the press continues to go up.  If we allow the cheeses to continue to accelerate at the same constant rate of 1 m/s^2 (remember, an unrealistically fast acceleration), we will continue to have a 2 Newton difference across the first cheese.  However the press will be providing a greater force than just those 2 Newtons because it has to "counter" all of the reactions from the entire stack of cheeses that have now been engaged.  Let's suppose, that after 10 seconds, the press will have reached 1/2 of it's final pressure.  If we're looking at a 6 inch cheese pressed at 6 psi, then we'll need about 750 Netwons of final pressing force, half of that, then puts us at 375 Newtons.  At that point, our 2 Newton difference between the first cheese and the last cheese (which has almost no force differential across it) is just over 1/2% difference in force (and thus in pressure).  When we get up to full pressure, the difference will be closer to 1/4%.  However, what we've ignored is that when we get to full pressure, the acceleration of the first cheese will be essentially 0, thus the difference in force across the first cheese will be 0, and the difference in pressure between the first and the last cheese will be 0.

From this analysis (which is exaggerated to make the differences bigger) we find that: the first cheese in the press experiences more pressure than the last cheese, the difference lasts only so long as the cheeses are compressing, the difference is proportional to the rate at which the cheeses are accelerating, and, in an exaggerated scenario, this difference in force represents an extremely small difference in pressure.
Title: Re: Commercial Gouda press
Post by: smolt1 on November 01, 2012, 10:52:28 PM
So it's like when the long freight train pulls into town and slows down and stops. Then the engine reverses and the couplings between the freight cars start banging, first the coupling between car #1 and car #2 , then between car #2 and car #3, and down the line until it gets to the last car. Only then does the last car move. And then the whole train is moving in reverse ( until the engine stops accelerating in reverse ) . The energy gained in each coupling ( which probably is in the form of heat ) does not change the outcome.
Title: Re: Commercial Gouda press
Post by: bbracken677 on November 02, 2012, 05:46:44 AM
So it's like when the long freight train pulls into town and slows down and stops. Then the engine reverses and the couplings between the freight cars start banging, first the coupling between car #1 and car #2 , then between car #2 and car #3, and down the line until it gets to the last car. Only then does the last car move. And then the whole train is moving in reverse ( until the engine stops accelerating in reverse ) . The energy gained in each coupling ( which probably is in the form of heat ) does not change the outcome.

except that the engine does not stop once the pressure exerted on the first car becomes x amount. Acceleration stops once the engine stops accelerating and a balance is achieved in relative speed between the engine and cars.

Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on November 03, 2012, 03:42:26 AM
How
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on November 03, 2012, 03:42:56 AM
many
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on November 03, 2012, 03:43:23 AM
more
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on November 03, 2012, 03:43:49 AM
posts
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on November 03, 2012, 03:45:09 AM
before I become a mature cheese?

(yeah, I caved and quit, did not want to be completely annoying..)

Go gravity and energy!!
Title: Re: Commercial Gouda press
Post by: smolt1 on November 03, 2012, 11:16:27 AM
A cheese for your persistence!
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on November 04, 2012, 08:47:22 PM
A cheese for your persistence!

He he, someone noticed my stubborn... uh, I mean persistence!
Title: Re: Commercial Gouda press
Post by: H-K-J on November 05, 2012, 08:23:30 AM
I think I am gettin a headache :o
Title: Re: Commercial Gouda press
Post by: bbracken677 on November 05, 2012, 09:14:04 AM
I think I am gettin a headache :o

LOL  we have gone way out there!

The truth is out there!  I want to believe!  (x-files)
Title: Re: Commercial Gouda press
Post by: Alpkäserei on November 05, 2012, 05:00:25 PM
When pressing cheese, there is a latency. This is obvious, and we seem to agree on this. It takes time for the pressure in a cheese to resolve itself to the point where the weight will pass straight through unhindered into the next cheese in the stack.

But it seems to me that this takes longer than maybe we think it should. Like I said, I have pressed cheeses before in a stack, and can attest that the difference in pressing quality by location is obvious. Rotating is necessary. This can only mean that the theorizing and calculating is leaving out something very important. My guess, though I may be wrong, is that the latency factor is greater than we are giving it credit. It is kind of like the freight train analogy, we have to wait for all of the couplers to pull tight before the last car will move. But it is like a very very slow freight train, just creeping along.

In the early pressing stages, the amount of time the cheese is under the press does not seem to be long enough to arrive at equilibrium. Either that, or the proportion of time spent at equilibrium relative to unbalance is too small, resulting in inconsistent forming throughout the stack. There are 2 solutions to this problem. The obvious solution is to leave the cheese in the press longer. The only problem with this is that it results in an imbalance of the material within the cheese (certain compounds will want to make their way to the bottom, particularly during the early stages of pressing) and a poorly formed exterior (most surface imperfections need to be eliminated during the first hour or two of pressing, after this they are extremely difficult to erase)
The better solution is just to use a series of short early pressings with flipping and rotation between each one. It is a little more work, but yields ideal results
Title: Re: Commercial Gouda press
Post by: Mike Richards on November 06, 2012, 03:48:44 AM
Alpkaserei--have you seen this in both horizontal presses and vertical presses or just vertical presses?  I don't mind my analysis being incomplete--and it clearly is if reality doesn't behave the way my analysis describes it should (or I could have just made a mistake...).

I don't like the train example because the delay in the force reaching the last car is due to the distance required to travel before engaging each successive car.  When pressing a stack of cheeses (I assume, because I've never used a horizontal press) the cheeses are not left with any distance between (and, I suppose, if they were, the time required to engage all of the cheeses wouldn't count in the pressing time).

A better model, perhaps, is that of a spring and damper.  Most people are familiar with a spring (though they often have misconceptions about how they work...).  A damper is usually described as a piston, with holes in it, held within a sealed cylinder that is filled with some fluid.  When the piston is pushed, it travels through the cylinder, forcing the fluid to travel through the holes in the piston from one side of the cylinder to the other side.  Many automobile shocks contain dampeners and they are often found on doors to prevent them from slamming shut.  If the holes are large and the fluid has low viscosity (it's runny) then you can apply a great deal of force to the piston, and only supply a small deal of force in the opposite direction to the cylinder to prevent the cylinder from moving.  If the viscosity is high and the holes are small, most of the force that is applied to the piston will need to be applied to the cylinder in the opposite direction to prevent the cylinder from moving.  In both cases, the piston moves.  Regardless of the size of the dampening coefficient (how much damping the damper does), once the piston has reached the end of its travel, all force applied to the piston is transmitted directly to the cylinder.

If we go back to the cheese now, we can model it as a spring-damper system in series--that is, the cheese press pushes on the damper of the first cheese, which then pushes on the spring of the first cheese, which pushes on the damper of the second cheese, which pushes on the spring of the second cheese, etc.  If you imagined having a uniform mixture of curds and whey where the ratio of whey to curds was sufficient to prevent the curds from touching each other, this model would be pretty good.  Instead of  the classical dampener, we've left the piston (the follower) hole-free, and filled the cylinder (the mold) with holes.  As we press on the "cheese" the whey leaves the cylinder, damping the force of the piston.  In this case, we'd expect to see a lot of whey coming from the first few cheeses and very little, if any, coming from the last few for the first while of pressing.  In this model practically all of the whey would be pressed out before the curd started to knit (because the springs, the curd, wouldn't have to carry much load until all the dampers were completely bottomed out).

A better model, in my estimation, is that of a spring-damper system in parallel--that is, the press pushes on both the damper and the spring of the first cheese at the same time.  These two from the first cheese, then push on the spring and damper of the second cheese, and so forth.  In this model we can think of the curds as the spring and the whey in the mold as the damper.  When a force is applied by the press, a portion of it is supported by the spring--this portion of the force is transmitted directly to the next cheese (and through all of the cheeses).  The remaining portion of the force is carried by the damper.  How large this portion is and how much of it is transmitted to the next cheese depends on the characteristics of the damper.  If the spring is really weak, and the damper has a low damping coefficient (lots of holes and a non-viscous fluid), then we'd expect to see a similar phenomenon as we saw in the previous case--a lot of whey coming from the first few cheeses and very little (though a bit more) from the last few.  If the springs were not weak, and the damping coefficient high, we'd expect to see a more uniform loss of whey, though the first cheeses would still lose a little more than the last.

What might be the most accurate model would be to combine these two models.  The whey can be modeled as a damper, but the curd itself, if drained well, for example, is probably well modeled as a spring-damper system (though it probably is more like one in parallel than in series).  In this case, the whey has one damping coefficient (probably relatively small) and the curd's damper has a different damping coefficient (probably a lot higher).  If I recall correctly, you can combine the two dampers into an "effective" damper and you end up with a model like the second model, where the damping coefficient is somewhere in between that of the curd's and that of the whey's.

The relative intensity of pressure (or the force) experienced by the last cheese, when compared to the first cheese, depends on the stiffness of the spring (or the stiffness of the curd) and the damping coefficient of the whey/curd damper.  If the curd is very stiff, regardless of the damping coefficient, the difference in pressure experienced will be small, if the damping coefficient is large, regardless of the stiffness of the spring, the difference in pressure will also be small, however if the curd is not stiff and the damping coefficient is small, the difference will be large.  Of course, if things are more moderate, the difference will, too, be moderate.

Now, how to measure the damping coefficient and stiffness of cheese during pressing.

And despite writing all of this boring stuff at 0200 in the morning, I still don't know if I can go to sleep.  Curse this dumb cold...
Title: Re: Commercial Gouda press
Post by: Boofer on November 06, 2012, 08:39:11 AM
Thanks, Mike, I was just...ZZzzzzz....  :)

-Boofer-
Title: Re: Commercial Gouda press
Post by: H-K-J on November 06, 2012, 09:12:52 AM
LOL ;)
Title: Re: Commercial Gouda press
Post by: smolt1 on November 06, 2012, 11:43:15 AM
What happens to the curds and whey inside the mold as it is pressed is very complicated and is NOT a physics problem BUT. The forces on each mold in a horizontal or vertical stack is a physics problem and there are some truisms.

1 The cheese in a given mold will not " know " if what is pushing on its follower is another cheese mold, a spring or a long stick, or anything else. It will only " know " that it is a force of a certain magnitude.

2 The process of compression is 99.9 to 100 percent STATIC( very slow and very small movement). So any work done( and resulting change in energy) is almost 0. Once the cheese is fully pressed it is 0.

3 If you put a scale between each mold in a vertical stack and read the force(weight) on each scale, you will see that any mold in the stack has a force (weight) on it equal to the weight of all the molds above it plus the force(weight) applied to the top mold by the press.This is true( 99.99999%) at the start of pressing and( 100 %) at the end of pressing.

The components of the solution to a problem have to be separated to get an answer. For instance ,if I push on a giant oak tree for 10 minutes I have expended a lot of energy( I am sweating) BUT I have done no work to the oak tree( it didn't move)
Title: Re: Commercial Gouda press
Post by: Mike Richards on November 06, 2012, 07:16:35 PM
Thanks, Boofer.  I'm glad it helped put someone to sleep.  And, since I mentioned it and I know you all care, the "cold" that was keeping me awake turned out today to be strep throat.  No work for me tomorrow--for some reason the rest of the folks I work with don't want to get strep.

Smolt--I thought everything was a physics problem... ???
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on November 06, 2012, 07:26:18 PM
What happens to the curds and whey inside the mold as it is pressed is very complicated and is NOT a physics problem BUT. The forces on each mold in a horizontal or vertical stack is a physics problem and there are some truisms.

Why do you say this is not a physics problem? Sure, only the most sadistic of professors would choose this as a final exam question, but there are forces and energies and all kinds of good stuff involved. (Hmmmm.... I wonder if we could get a paper out of this... One of those novelty papers you see in the AMS Bulletin or Physics Today.)
Title: Re: Commercial Gouda press
Post by: mightyMouse.tar.gz on November 06, 2012, 07:27:21 PM
No work for me tomorrow--for some reason the rest of the folks I work with don't want to get strep.

Wusses! I swear, you never know who your true friends are till you have strep throat do you!
Title: Re: Commercial Gouda press
Post by: Alpkäserei on November 06, 2012, 08:43:06 PM
Smolt, do you have observed proof of what you say? Because I have observed proof to the contrary.

When I put multiple cheeses in a vertical stack, the top cheese releases a great deal of whey, while the bottom cheese releases very little. Yes, I could leave them in longer until the forces equalize but this is bad practice. The turnings need to follow a regular time schedule for good rind formation.

We all know that it makes no difference to the cheese where the forces come from that are affecting it, but does that mean we can't ask what is going on? Sure, it doesn't actually get us anywhere but who cares? It's enjoyable to look into the physics of a problem and figure out what is going on.

Mike I think you have a pretty good understanding of the situation. I suspect that the damper illustration might be getting close to the reality.

Also another thing to consider, some work goes into compression resulting in heat. Other work goes into a chemical process going on in the curd that causes the cheese to fuse together. The goal of pressing hard cheeses, at least in my experience, is to cause a fundamental change in the makeup of the cheese. We can observe this when we compare a pressed alpine cheese with a Parmiggiano Reggiano. The parm is not pressed, and the structure of the inside is radically different than that of my Alpkäse even though the make procedure is almost identical up to this point.

It takes energy to cause this to happen, a significant force applied directly to the cheese causing the curd to 'knit'. This requires heat and a compressive force to happen. We can observe that an increase in one or both of these factors results in a quicker, more complete knit while a decrease has the revers effect.

Furthermore, the internal structure of a pressed cheese in changed in more ways than just being more compact. There is a obvious difference in texture. I submit that the act of applying a great deal of compressive force to the cheese results in a fundamental change of the structure of the cheese -i.e. a chemical reaction. This reaction by necessity uses supplied energy to happen. The result of this would be a reduced force over the span, would it not?

This helps to explain a few things about pressing, such as why it is so important to keep the cheese warm, why it is important that the proper pressure be applied, etc.

Just some thought, probably some errors in there.
Title: Re: Commercial Gouda press
Post by: Mike Richards on November 07, 2012, 10:09:36 AM
This has been a fun discussion.  It seems time to do some experiments.  Here are a couple I propose--if you think they will fail to elicit an answer to the topic at hand, let me know.

If a stack of cheeses will, regardless of the mechanism, reduce the load (force) that is transmitted from that applied by the press on the first cheese to that experienced by the last cheese, then we would expect to see a reduction of load across a single cheese as well.  Agreed?  Then, I propose that everyone, during there next cheese make, put a scale under the cheese (perhaps cover it in plastic wrap or something...) and measure whether or not the actual force the scale weighs is less than the force applied by the press.  If you've got two scales, you could put one between the press and the follower and one between the cheese mold and the base of the press.  In both cases, unless you press horizontally, you'll need to subtract the weight of the cheese, mold, follower, (and additional scale if using two) from the lower scales reading.

If someone with a multi-cheese press is willing to play, their result would be even more convincing--they could do it with 2 scales as well, 1 between the press and the follower of the first cheese, and one between the last cheese and the base of the press.  Again in a vertical setup, they would need to subtract the weight of all the cheese, molds, etc. from the lower scales reading.

If there is a reduction of load, then we know the cheese is behaving more like a damper than many of us could have imagined (me included in this--despite my long boring discussion of how to model the cheeses, I really expect almost no difference, but like I said, I don't mind being wrong).  If the loads are the same, then we know the cheese acts a lot more like a spring.  If there is an increase in load, we'll know we've broken the laws of nature, and we can be even more impressed with awesomeness of cheese.  ;)

I'll see if I can make this happen on my next cheese--though the scale we have that would work for this (a bathroom scale) isn't exactly trustworthy...  It would be a lot more interesting to have more people participating and reporting their results.

Let me know if you're in.
Title: Re: Commercial Gouda press
Post by: bbracken677 on November 07, 2012, 10:17:24 AM
This has been a fun discussion.  It seems time to do some experiments.  Here are a couple I propose--if you think they will fail to elicit an answer to the topic at hand, let me know.

  Then, I propose that everyone, during there next cheese make, put a scale under the cheese (perhaps cover it in plastic wrap or something...) and measure whether or not the actual force the scale weighs is less than the force applied by the press.  If you've got two scales, you could put one between the press and the follower and one between the cheese mold and the base of the press.  In both cases, unless you press horizontally, you'll need to subtract the weight of the cheese, mold, follower, (and additional scale if using two) from the lower scales reading.



Let me know if you're in.

The main problem with the single mold press trial is that the difference is likely small enough to be measurable only by very accurate equipment....

I will be checking for an increase in temp the next time I make a cheddar and push the press to it's limit...I am hoping that perhaps the change in temp will be measurable. I think that a multiple mold pressing would, perhaps, yield a measurable difference.
Title: Re: Commercial Gouda press
Post by: H-K-J on November 07, 2012, 10:51:33 AM
I was going to wright something important here but I got a brain cramp :o
Title: Re: Commercial Gouda press
Post by: Mike Richards on November 07, 2012, 11:00:21 AM
Quote
The main problem with the single mold press trial is that the difference is likely small enough to be measurable only by very accurate equipment....

If I'm doing a 6 in wheel and pressing at 4 psi, I'll need 113 pounds.  My bathroom scale has 1 lb gradations, so I should be able to detect about 0.5 lbs in difference.  If the difference is less than that--so that I can't detect any difference--then we could reasonably say the maximum load lost represents less that 0.5% per cheese.

Below is the stack size and % difference between 1st and last cheese:

5  -->2%
10-->4%
15-->7%
20-->9%
30-->14%
50-->22%

So, this brings up a couple of questions.  How many cheeses are put in a commercial horizontal cheese press?  How much of a difference in pressure is cause for concern?

Recall this is the maximum loss possible based on my inability to measure smaller differences than 0.5 lbs.  If the actual loss across a single cheese is less, the overall loss will, also be less.
Title: Re: Commercial Gouda press
Post by: Mike Richards on November 07, 2012, 11:01:17 AM
I was going to wright something important here but I got a brain cramp :o

You and Boofer sound like some of my favorite kids to have in class... :P
Title: Re: Commercial Gouda press
Post by: bbracken677 on November 07, 2012, 11:08:05 AM
I was going to wright something important here but I got a brain cramp :o

LOL  love it! 
Title: Re: Commercial Gouda press
Post by: smolt1 on November 07, 2012, 12:35:29 PM
Alpkäserei, I can see how you get the results you talk about if you use a press that screws down and does not keep the force constant. Do you have a picture of your press?
Title: Re: Commercial Gouda press
Post by: terry@dairy fab on November 07, 2012, 02:32:20 PM
This whole conversation reminds me of equipment I built and installed for the large scale commercial cheddar makers around the country for a previous employer. There was a base unit that sat under an 18 foot tall tower that milled curd was vacuumed over to and the cheese was formed into 40 lb. blocks all the while under a vacuum that pulled any residual whey from the cheese. The weight of the18 foot column of curd  along with vacuum knit the curds together and we were able to pull out a 40lb. block of cheese every 90 seconds. An average plant had anywhere from 6 to 8 towers with the largest plants had well over 20+. The blocks came out tightly knit and pushed into bags and went straight to the cryovac and off to the boxer. I don't know how this fits into the conversation, but just brought back fond memories of being in different cheese plants everyday.

terry@dairy fab
Title: Re: Commercial Gouda press
Post by: Boofer on November 08, 2012, 09:18:58 AM
Wow, you've painted a picture in my mind that's astounding.  :o

18 foot tower...20 of them...40 pound blocks of cheese...vacuum sucking whey...tight knit...every 90 seconds. Wow again!  8)

-Boofer-
Title: Re: Commercial Gouda press
Post by: terry@dairy fab on November 08, 2012, 09:51:17 AM
Boofer, if you go to www.stoelting.com (http://www.stoelting.com), click process solutions, click cheese making, click blockformers you can see pictures and specs from their brochure. I was with them for 25 years, built probably 150 of these and later was their technical service installer responsible for the full line of cheese making equipment. Now I just build and repair curd knives in my own shop 2 miles from the house. I do sometimes miss getting into different plants across the country, but much prefer to work in my own shop and not travel 28 days a month., and it still keeps me connected with the industry and customers I worked with in the past. The best of both worlds for me.

terry@dairy fab
Title: Re: Commercial Gouda press
Post by: Boofer on November 09, 2012, 08:53:31 AM
Hey, Terry, thanks for that.

One more thing I can take off my "Things I Didn't Know I Didn't Know" list. ;)

-Boofer-
Title: Re: Commercial Gouda press
Post by: bbracken677 on November 09, 2012, 09:07:38 AM

One more thing I can take off my "Things I Didn't Know I Didn't Know" list. ;)

-Boofer-

LOL that is a very Douglas Adams'ish remark ...