Rotek has just completed
building and furnishing the QA/QC Lab. This lab will take us from limited
visibility to a clear vision in terms of supplied raw materials, WIP and
finished parts, and enable us to make better informed decisions about potential
process changes and shipment of final product.
In the past, we relied upon
vendor promises and visual tools to qualify materials and processes. Many times
this left us with a limited visibility and understanding of what we had received
in raw materials or what we had just produced. Now we have the ability to more
accurately assess these incoming materials and the processes used in creating
our finished parts. This is a win-win for us and our final customer. Let’s look
at some of the more important equipment in the lab and see how its used:
Stereomicroscope
This tool lets us take a closer
look at incoming palletized resin. We look for things such as tails on the
pellet, basic pellet geometry and pellet count per gram. These tests are
necessary to qualify our resin supplier. If there were significant tails,
geometry problems or if the count were significantly outside of our target range
then we would have problems grinding the resin on our pulverizing mill. Grinding
problems will lead to poor powder flow and distribution in the mold yielding
inferior parts. This is a QA/QC checkup on our supplier
Melt
Index
This tool measures the flow of
the resin (pellet form) through a standard size orifice within a standard amount
of time. This test lets us know the incoming quality of the pellet from our
vendor. It let’s us know if we are receiving the proper grade of resin and if
this grade is within the proper flow spec. This is a QA/QC checkup on our
supplier.
Densimeter
This tool enables us to check
the specific gravity or density of a resin pellet to determine if we are
receiving the proper grade of material and that the material is within density
spec. Again, this is a QA/QC checkup on our supplier.
Carver
Press
This equipment tests for
contamination within our resin and pigment. It is used to qualify incoming
materials or mixed materials within our process. This equipment also allows us
to make certain “press-outs” that can be used for further evaluation at other
labs. This is a QA/QC checkup on both the supplier and our
process.
Ro-tap, Bulk Density,
Dry-Funnel Flow and Throughput
These three pieces of equipment
are crucial to our process in that they help us determine if our pulverizing
mill is working within process targets and helps us determine the quality of our
ground resin. The Ro-tap test measures particle size distribution. It let’s us
know if we are within the target 35 mesh grind for our resin. It will help us
determine process problems like fluffy powder, damaged sifter screens, and blade
gap adjustments. The bulk density cup analyzes bulk density. This let’s us know
about powder flow and mill temperature ranges that are critical to burning tails
off of the resin particle are correct. The dry-funnel flow test lets us know how
our powdered resin will flow relative to time and the quality of our grind
(poor, average, good). The throughput test measures how much resin we are
grinding per hour on our mill. This test let’s us know the approximate time for
a blade change. These tests are QA/QC checkups on our pulverizing process once
we have ground the pellet into powder form.
Impact
Tester/Freezer
This equipment tests the low
temperature and ambient impact resistance of our molded resin. This is probably
the most important test to a molder next to the dry-funnel flow test. This test
let’s us know how a resin will perform given a certain process and within
various stages of cure (under through over) This test is primarily used as a
QA/QC checkup of internal processes, however, it can be used to qualify incoming
material as well.
As you can see, with the
building of this lab, our visibility has been greatly enhanced. We will be able
to more accurately assess incoming material, process changes and their impact
upon final molded parts.