Turret presses with tool perform inline marking
August 14, 2003
Custom metal fabricator Total Metal Products, Dallas, had a need for part marking that would be both accurate and cost-effective for small quantities. The company supplies punched parts in single and small-lot quantities of 200, 300, and 400 on a just-in-time (JIT) basis. Its customers include manufacturers in the telecommunications, aerospace, mass transit, and oil refining industries.
The company provides a range of fabricating services, including turret punching on four Amada 30-ton, 58-station turret presses. In addition, the company operates press brake, laser, welding, painting, plating, assembly, and kitting equipment.
It is located in the Texas telecom corridor where, according to the company, job shop failures have been high. It said it has weathered the economic downturn by adding value to parts, such as marking parts with identifying assembly codes to speed the customers' assembly operations.
"Marking sheet metal parts with assembly codes and numbers is an important requirement for our customers who need small quantities of different parts," said Jackie Robertson, senior programmer.
In addition, a growing number of customers require part traceability as part of their quality programs. Traceability becomes a major production issue for customers with multiple products and part families involving many machines and production lines.
The method the company had been using to mark different parts in quantities of a few hundred using an alphanumeric stamp was slow; subject to error; and produced coarse, uneven images.
"The customary way of using an alphanumeric stamp for different part runs in quantities of a few hundred was slow and required hand labor," Robertson reported. "Our press operators set the numbers and characters for each job by hand, a process which was tedious, subject to error, and the markings were not always consistent from part to part," he said. The alphanumeric stamp also produced coarse, uneven images, he added (see Figure 1).
"To eliminate secondary operations, we wanted to do part marking on the turret presses while the parts were being punched," Robertson said. "We tried other wheel-type tools on our turret presses, but they didn't do the job.
"Marking them with our laser was another option, but most of the parts that require marking are aluminum, which can damage the laser," Robertson added. "Furthermore, going to the laser [would have] created an extra part move we wanted to avoid."
The fabricator needed a tool that would mark different material types and thicknesses, Robertson added. Even though about 80 percent of the company's marked material is 5052 aluminum in thicknesses of 0.032 to 0.125 inch, it needed to be able to mark the other 20 percent also.
"We didn't think there was a workable solution until we posed the problem to our Mate Precision Tooling salesman," Robertson said.
The Mate Sheetmarker tool, which is assembled onto a turret punch machine and automates the marking operation, can be used on both hard and soft materials, including aluminum. The tool marked this complex aluminum part with different size and font characters using the turret punch press’s programming software.
Mate recommended its Sheetmarker® tool, which is assembled onto a turret punch machine and automates the marking operation. It can be used on both hard and soft materials, including aluminum (see Figure 2).
For part traceability, the Sheetmarker can be set up to add such data as pallet number, machine number, sequential serial number, time, and date, according to the company.
In addition, the tool is touted to be suitable for small parts punched out of large sheets in grids, which matches Total Metal Products' needs because many of its jobs are punched from 4- by 8-foot sheets in grids of up to 50 parts.
Robertson said he considered Mate's claim that the tool could be programmed to mark anywhere on the sheet without marking the backside or deforming the material, resulting in smooth and consistent images, flat sheets, and marked surfaces without burrs or sharp edges.
Robertson examined the tool construction and components. The tool itself comprises a diamond insert, an insert retainer, an insert holder, one spring, and a Sheetmarker roller die. These components are assembled into a standard Mate Ultraform® 1/4 (B) station holder.
At first Robertson was skeptical that the Sheetmarker could do the job but agreed to buy one with the condition that Mate guarantee its performance and set it up in the machine to work properly with the fabricator's Amada Vipros 358 King and 18p controller.
The guarantee had to include assurances that the tool would work with different materials. Robertson wanted to be sure that the tool could handle different material types without a lot of downtime for changeover from one material to another.
Robertson estimated it took about six hours to program the Sheetmarker tool for the machine using existing software, which included setting up code parameters for different part types, and then verifying the tool's performance on sample parts.
He said that using the tool and the accompanying turret press software required training and some getting used to. Mate provided on-site training so that Robertson and the operators could test it on different part projects while learning what the different components of the tool could do and how to control the depth and quality of the markings.
Controlling the depth and quality of the markings depends on controlling the press, tool, and material variables. The 150-degree diamond insert and light-duty spring allow for a shallow marking; the 120-degree insert and heavy-duty spring make a deeper marking. The heavier-duty the spring, the more forceful the impact and the deeper the marking. Other variables are adjustment of the punch press ram; the rate that the press is advancing the sheet; the material type and thickness; and thickness variations within individual sheets.
Angle settings engraved into the surface of this 1/8-in. steel part are crisp and permanently marked on two sides of the part.
Robertson said he was happy with the result. "It's fast, accurate, and eliminates hand labor to do the job.
Robertson reported that both of the new tools paid for themselves the first two months that they were used, and that he had no replacement part problems with the tools. "We've operated the first Sheetmarker for nearly a year and a half without replacing the diamond insert because it just doesn't wear out," he said.