Molded part manufacturing problems

[kalipa]

i work in a company that manufacture car light and its my first job am from school,my boss gave me a project ,nw i dont know were to stat ive collected data.the parts are moulded in an moulding machine(BMC)the material is mozolit its from france.the temparature on the mould is 160 degrees when its heated up.need help ASAP
PROBLEM:
Assembly lines found that the screw hole diameter was too big on some reflectors.
•326 A (LHD RH Reflector) found oversize holes on the 020 (RHD RH reflectors on hole A (3.65mm screw)

•005A found oversize holes on the 020/010 (4.5mm screw)
There are usually only a few reflectors rejected at assembly for oversize holes found in one bin or a few consecutive bins.
An audit was conducted on 7/11/2013 on two bins in the WIP rack.
Pin gauges were used to determine what size gauge would enter the hole.
RIGHT HAND DRIVE (326 A)
Right hand Left hand
A(mm) B(mm) A(mm) B(mm)
3.5 3.6 3.6 3.6
3.5 3.6 3.6 3.6
3.5 3.6 3.6 3.6
3.5 3.6 3.6 3.6
LEFT HAND DRIVE (326 A)
Right hand Left hand
A(mm) B(mm) A(mm) B(mm)
3.5 3.6 3.6 3.6
3.5 3.6 3.6 3.6
3.5 3.6 3.6 3.6
3.5 3.6 3.6 3.6
The A hole is smaller on the Right hand on both LHD & RHD


Interviews were held with the setters, tool polisher and tool maker to ask their input on what may cause the hole variation, but there were no possible causes raised.
The assembly line operators were interviewed and they said the holes are over size when the parts get to them (as opposed to the screw being inserted incorrectly and stripping the hole).
The torque on the assembly station had previously been raised on the RH due to the hole being under sized and not bottoming out.

[GlennD]

Is the bad hole still round on the parts?

[Timelord]

If the parts are varying as they come out of the mold, I would suspect that the mold cooling is not consistent from shot to shot. Try these guys if that is the problem. http://pulsecooling.com/

Timelord