Scrap
Submitted by Dave Andersen on Mon, 11/24/2008 - 10:48am
We are trying to determine how our organization is doing with internal scrap numbers compared to other molding plants in the industry. Our internal scrap, including purging, parts and runners is 1.7%. We are a captive injection molding closure facility, how does this compare to other operations.
Comments
Industry norms for Specific Energy
I would like to know the Injection Molding Industry norms for Specific Energy (kWh/kg) in general, and specifically for uPVC if possible. We run at around 0.9 kWh/kg having about 20% scrap as a result of not having hot runners (unsuitable for PVC).
Any data / sites bench marking this industry would be much appreciated.
Hiding Cosmetic Defects
Is there a product out there that can be applied to plastic parts that will mask minor defects like a small speck of contamination or splay rather than throw away a huge part because of it? I'm thinking about something analogous to putting make up and hiding freckles or pimples. I would certainly appreciate any direction anybody can give. Please e-mail me at: kato2181@sbcglobal.net.
Flaw repair coatings
Check out
http://www.chem-pak.com/catalog/plastic_molding/per-fix/abs.html
Chem-Pak makes Flaw repair coatings to hide surface defects.
242 Corning Way
Martinsburg, WV 25401
Toll-Free:800.336.9828
Vishu Shah
Consultek
www.consultekusa.com
Hiding defects
You could talk to your plastic supplier to find out a solvent that would desolve the plastic involved without cracking it. (this would not work for PP or PE) Then you could make up a paint from some chopped up bad parts and use a paint brush or spray gun to coat the part with a cosmetic paint to hide the defects.
Less than 2% SCAP should be
Less than 2% SCAP should be considered very good. I presume you are using hot runner tools and not changing colors frequently. If you change colors and need to purge, then 2% would be considered excellant.
Scrap
Thanks for your response.
About 95% of our tools are hot runner tools. About 50% of them are direct gated and the other 50% generate a cold runner that is ground at the machine and re-used. We probably average 12-14 color changes every seven days.
Dave