Overview
There
are thousands of small decisions to
be made as the design and manufacturing
process for a product evolves. These
decisions generally revolve around picking
the appropriate compromise among a variety
of competing factors; factors such as
cost, speed, appearance, convenience,
et cetera. These decisions are made
easier when you pick one factor and
"put a stake in the ground." For us,
that factor was quality.
The stories and images below are presented
as our way of providing you some insight
into the detail and depth of our attention
to quality. When you get to the heart
of the matter, quality is not about
forms, meetings, tests, or ISO certifications;
instead quality is an attitude, a discipline,
and a perspective. Techniques and tools
related to quality, such as ISO 9001
procedures, are like any other tools;
they can be used correctly or used poorly.
Many of our sources are from China and
Taiwan, places that are occasionally
known for a lack of quality. We found
many factories that fail to understand
quality and a few that "get it." Direct
experience with a supplier and their
products is the best way to tell the
difference. Finding the right suppliers
takes a great deal of time and money,
but it's an investment that provides
a competitive advantage. Please don't
bother to ask us who our suppliers are,
in most cases we are not willing to
discuss the subject.
Machine Production
To start with, let's recognize that ultimate machine precision is not a suitable goal, unless of course, cost is not a concern. The image to the right is a link to a QC document that defines the level of precision appropriate for the PCNC 1100. In this context, quality is not the degree of precision the machine is designed for; rather it is the ability to always meet the precision specifications.
The tests described in the QC document are performed on every machine, with the exception of the Optodyne test described near the end of the document. That test is done on every 20th machine. The Optotyne laser Doppler displacement measuring system (www.optodyne.com) is an exceptional tool, normally only used to calibrate high-end machine tools. The link below is a 6 meg video, a test on basic linearity for the X axis. The machine moves 10 mm at a time while the Optodyne is recording position. Two readouts on the laptop are command position and actual position, in mm.
One simple principle we used when looking for suppliers was to try and make sure that the product we were interested in was not the best thing they have ever made. The photo below is from a typical Chinese drill/mill factory, where the best product they know how to make is a simple drill/mill, similar to those found in discount catalogs. We worked with several such companies, all the way to delivering prototype CNC mills. None of them were good enough.
The manufacturer we partnered with for production of the PCNC 1100 has extensive experience producing larger CNC machine tools for the domestic market in China. One of their VMCs is shown here, behind our friend and interpreter, Ms Chi Jing. One of the Chinese engineers put it pretty well when we were discussing some difficult details of producing the PCNC 1100, he used the American idiom “Piece of cake.” For them it was true, for others we had presented challenges they simply could not meet.