Zero defect hole processing technology

Today's automotive industry requires component suppliers to have strict processing part size and precision control capabilities, and one million parts of the defective product is one hundred percent defective for the part itself. Fortunately, auto parts manufacturers are getting help from machine tool suppliers who have zero defects in machined parts.

American Turned Products (ATP), located in the Erie region of Pennsylvania, USA, has been a component supplier to the automotive industry since 1984, and currently accounts for approximately 70% of the company's sales. According to Harry Eighmy, the company's vice president of manufacturing, ATP also used traditional oilstone honing equipment for hole machining a few years ago. At an international metalworking technology exhibition, they found that the single-stroke machining machine of the US ENGIS company's multiple diamond-plated tools has a significant technological advantage over the equipment used at the time of ATP.

The traditional oil stone honing is processed through a hole repeatedly by a diameter-expanding tool. The single-stroke hole machining machine has a plurality of solid cylindrical cutters, and the size of each knife is sequentially increased. The typical process is as follows: the machined part is placed on the jig of the rotary table. When the machined part is transferred to the first station, the first tool is processed in a single stroke, and the part is transferred to the second station. The tool with a slightly larger diameter is machined accordingly, and the part is rotated until all the tools have been machined. Each time the table rotates, each part has a corresponding part to be processed, and a finished product is completed.

The diamond tool not only has high wear resistance, but its wear is distributed to all the tools, so that the final state of each machined part is more consistent, and the downtime required to replace the tool is shorter and the production efficiency is higher. And diamond tools are cheaper than traditional honing tools.

In view of the above advantages, ATP purchased two ENGIS semi-automatic hole machining machines and an automatic machining system for the production of automotive parts. As with most metalworking processes, machine tools are just one aspect of the hole machining process. The sales representative of ENGIS works with the user to clarify the machining application to be completed, recommending the most efficient machining methods, part fixture systems, machining coolants, parts inspection, and automatic configuration options. Processing example: ATP processes 1215 alloy quenched parts on a turnkey machine equipped with automatic loading and unloading. It is required to finish 35mm deep blind holes on parts with diameter of 25.4mm and length of 50mm. The machined hole size tolerance is 0.01mm, surface roughness Ra 0.7 μm.

In the automatic loading and unloading system, discrete heat-treated parts are fed into the conveyor by the rolling feeder. A small FANUC robot stands at the operator's position at the front end of the machine, takes the workpiece from the conveyor, and sends it to the machine's rotary table. The loading station is in the fixture chuck. The machine rotary table brings this engine speed control part to different processing stations. Thus, a part passes through six single-stroke diamond hole machining tools with increasing diameters. When the part is moved to the unloading station, the robot moves it from the fixture chuck to the inspection station. If the part is within the acceptable range, the part will pass through the inspection station to the discharge conveyor and will eventually be sent to the collection basket outside the machine fence.

Mr. Eighmy pointed out some of the advantages of automatic machine tools. The automatic loading and unloading package is not very expensive, probably only half of the manual machine, and the footprint is comparable to that of manual machines. The machining cycle of the two machines is the same, 9 seconds, but the automatic machining machine can run continuously, and the parts output is increased by 30% to 40%. In addition, the automatic hole machining machine guarantees a higher dimensional tolerance of 0.0025mm to 0.005mm and a hole surface roughness of Ra0.25μm to Ra0.3μm. The most important consideration is that the automatic machining machine eliminates human error and guarantees that each part is processed in exactly the same state, which is the only way we can ensure zero defect machining.