Taking the measure of profiles
The problem has vexed extruders since the first profile was pulled through a die many years ago. That problem is how to determine if you've made a good part from material that is often soft, flexible ...
The problem has vexed extruders since the first profile was pulled through a die many years ago. That problem is how to determine if you’ve made a good part from material that is often soft, flexible and formed into complex shapes.
Sam Melamed, president of PLV Systems Inc., says traditional methods used to measure profile dimensions give limited information because of the way in which the profile is measured, and also what is measured. He has developed a technology he believes effectively addresses both of these shortcomings
At present, calipers, gauges or shadow graphs are the most common methods used by extruders to measure profile. All of these methods are manual, and rely a great deal on subjective interpretation to determine whether or not a part is in or out of specification. More significantly, he reports, the limited data generated from these techniques very often does not provide the critical information needed to determine whether a part is functional, and good, or not so.
PLV’s Non-Contact Profiler incorporates a “flex-point” system of measurement based on automated imaging and specially designed software programs. The net result, says Melamed, is a profile measurement system that is not only more repeatable and accurate, but one that provides more and better data about the quality of a part.
“We’ve taken a different approach to measurement,” Melamed says. “We feel orientation and function determines what you should measure on a profile. We ask, what is it that makes this part work? To do this, you have to break away from the drawings.”
Melamed notes that a caliper or shadow graph measurement may show that a profile dimension is in spec, but the measurement may not have any relevance to the part’s function.
PLV’s Non-Contact Profiler, model NCP-FS-200, is designed for off-line use. A flatbed scanner is used to image a cut cross-section of an extrusion. Programmed software calculates dimensions and compares the measured dimensions to the upper and lower tolerances for a particular measurement. Each value is reported as a pass or fail. As well, out-of-spec dimensions are displayed in red lines on the computer screen. The data can be imported to SPC software and later retrieved for analysis or quality validation requirements.
The company also offers an on-line system which is designed to measure a profile just after it is cut using a high-speed video imaging camera. At present, because of lighting limitations, the on-line system can only measure external dimensions of a profile.
Melamed has sold profile measurement systems to Royal Group Technologies, Standard Products and others through equipment distributor Control Solutions Inc., based in Brampton, ON. He believes the extrusion industry is ready for the next step in measurement technology. “The profile market is very competitive right now and customers are demanding high quality. Companies that make garbage profiles are going to be in trouble.”