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| Author | Topic: Warping of 6' Parking Blocks |
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rharb280 Member Posts: 4 |
posted October 19, 2002 01:03 PM
   
Our Company Makes 6' Parking Blocks with a 150 mm 26-1 Extr. 50%LD 50% Hd Sometimes When put in a parking Lot we have trouble with them warping a Month after their Insalled Waht Could be the Prblem R.G. Harbour IP: Logged |
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Peter P Senior Member Posts: 61 |
posted October 19, 2002 05:32 PM
Could you explain what a parking block is and describe the profile shape. You say it is 6 foot (in length I take it) what are the other dimensions? What do you mean when you say that you put them in a parking lot? Are they fixed in some way? We need a lot more information if someone is going to be able to help you. Regards, Peter P IP: Logged |
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rharb280 Member Posts: 4 |
posted October 20, 2002 04:09 PM
Yea Sir,Our Parking Blocks or Saftey Stops are the Same as Concrete,except recyled Plastic 6" squared Bottom Triangling down to a 2" top 6" Tall.Oh and 4% Color Con. with UV INH.They Are installed with 3,12" Steel spikes. Thanks R.G. Harbour [This message has been edited by rharb280 (edited 10-20-2002).] IP: Logged |
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Tom C Moderator Posts: 737 |
posted October 20, 2002 08:59 PM
Likely your problem is the result residual stress in the block caused by the cooling process during extrusion. These stresses may be relieved in the hot sun, causing the block to warp. The solution would be to minimize stresses caused by an uneven cooling process. This might not be so easy given the cross section. This is not my area, but some type of system where the block is kept in it's final shape during a slow cooling process, or reheated for a while, may relieve the stress while maintaining the shape. Tom C IP: Logged |
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Steve H Moderator Posts: 386 |
posted October 21, 2002 12:59 AM
G'day RG Welcome to the single screw forum- Uneven cooling is a posible cause here, the shape you are extruding would be tricky to cool. How are you cooling it currently? Colourants and blends of materials can also cause post extrusion warping, I presume you are mainly using reclaimed materials for this product? Steve H IP: Logged |
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Peter P Senior Member Posts: 61 |
posted October 21, 2002 04:18 AM
Tom & Steve are probably right - residual stresses (frozen-in stresses) are the cause. The dimensions of your profile make it difficult to cool uniformally - the outside layers will cool much more quickly than the core, which can relax during the cooling process. The surface stresses will relax at a later time - accelerated in warm weather. One solution would be to extrude the profile into a cradle of similar dimensions so that it cannot warp and anneal it and cool it very slowly to release the stresses. Regards, Peter P IP: Logged |
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rharb280 Member Posts: 4 |
posted October 21, 2002 06:20 PM
Tom,Steve& Peter Our Molds rotate in a large water vat that has 5 Large fan that cool the water,simular to car Rad,s working together,also the molds are 24',which seems kinda long to me.Ive only been doing this 15 Months,Oh and yes it is reclaimed material.The ones I pulled today ,I let cool in the Molds and seem much better but if Businees picks up your Post Extuded cooling Idea will do the Trick I think Thanks R.G. Harbour IP: Logged |
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rharb280 Member Posts: 4 |
posted October 21, 2002 06:36 PM
Tom,Steve& Peter Our Molds rotate in a large water vat that has 5 Large fan that cool the water,simular to car Rad,s working together,also the molds are 24',which seems kinda long to me.Ive only been doing this 15 Months,Oh and yes it is reclaimed material.The ones I pulled today ,I let cool in the Molds and seem much better but if Businees picks up your Post Extuded cooling Idea will do the Trick I think Thanks R.G. Harbour IP: Logged |
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