Sheet-metal fabricator overhauls quality control process with laser scanner
Dumur Industries, of White City, Sask., is on a mission to make sure bad parts don’t go to its customers. Dumur, a contract sheet metal fabricator, provides its products to the electronics and computer industries, as well as manufacturing aftermarket automotive parts and final weldments for Canada’s Department of National Defence.
The shop has four turret-punch presses, three press brakes and a number of CNC mills, but the company found that none of its laser or waterjet subcontractors could provide the quality control documentation it needed. As a result, Dumur’s sampling plans were rigid and labour intensive, and the shop was forced to check as many as 40 percent of its parts for some jobs.
According to Bob Dumur, president of Dumur Industries, the inconsistent quality of subcontracted parts meant the company needed to find an accurate, efficient way to measure parts with tolerances from 0.002 inches to 0.008 inches. Dumur was providing parts to a General Motors division that demands its manufacturers comply with a production part approval processes. These processes require suppliers to document verification of every dimension of each subcomponent.
As a result, Dumur needed to overhaul its quality control (QC) process to eliminate inconsistencies and comply with ISO 9002. The company began reviewing a number of digitizing and scanning systems, and selected LaserQC from Waterloo, Ontario’s Virtek Vision.
"In the past, some inspections took two or three hours, especially for a computer chassis with up to 300 holes," says Dumur. "Today, they take two minutes."
The new QC system uses a laser scanner to measure the part and compare its dimensions to an original .dxf file. An on-screen display of the comparison provides immediate visual feedback on out-of-tolerance dimensions and shows any bad dimensions in red.
Dumur says it’s not unusual for the shop to reverse engineer parts for farm implements, working from cardboard cutouts of broken or worn parts. Although the shop doesn’t always process the parts, it can create a CAD file in .dxf format. The Laser QC operator scans the cutout and can e-mail the file to another shop where it is cut using a laser or plasma torch. Sometimes, the process works so well, customers can drop off a template at Dumur, drive to the other shop and find the part being cut.
Dumur Industries’ largest use for the laser scanner is incoming inspection in its quality control department, where outside part inspections are performed and daily inspection reports are produced to meet customers’ standards. Dumur has sent LaserQC reports to General Motors for the past two years.
Bob Dumur says the scanner automatically calibrates itself before each scan to help ensure its accuracy. Dumur personnel also use the laser scanner to check the calibration of punch presses. Every Monday, they produce test patterns by running each press through the XY axis in a specific material thickness and check each part dimension on the Laser QC to verify that the machines are within tolerance. The results are then graphed to call attention to press wear before it becomes a problem.
Recently, the company found a new use for the laser inspection system: as a tool for a visiting service technician. A turret punch press was out of tolerance due to several separate problems, and the technician spent several days checking variables to find the solution. For every adjustment or part replacement, the technician ran a test pattern and measured the holes.
"Someone suggested he use the laser scanner," says Dumur, adding that the idea made sense because the technician had to deal with multiple causes and make small changes. Dumur also says the repeated manual measurements of the test parts were difficult and time consuming, whereas a laser scanner can provide the critical dimensions in seconds.
"The technician had never seen the machine and was amazed at how much more it let him accomplish," says Dumur. "Two minutes per test versus 30-45 minutes can do a lot to reduce service call costs and equipment downtime."
Alison Dunn is the assistant editor of PEM Plant Engineering and Maintenance.