MMS Blog

By: Matt Danford 1. November 2018

The Fixture Niche

Some machine shops take on work that does not necessarily jibe with their capabilities. That is not the case for Contour Precision Milling & Machining. Instead, this Northeast Ohio shop has chosen a particularly specific niche: low-volume, repeat jobs involving non-round, non-square milled components, particularly castings and forgings. Although this oddly shaped work requires substantial planning and problem solving to develop an effective machining strategy, the shop’s extensive engineering capacity and expertise in designing and building custom fixtures enable it to excel milling these types of challenging parts on equipment including pallet-fed horizontal machining centers and five-axis machines.

Designing and building its own workholding devices is one of the most important ways Contour Precision helps customers get products to market fast. These tasks fall largely to people such as plant manager Brian Whitt, who started as the shop’s first apprentice more than 20 years ago, and senior manufacturing engineer Mike Kerecz, a nine-year shop veteran. The fixtures they make for castings, forgings and other components with complex geometries are all different, but many of the same principles and strategies apply. Here are a few examples:

American Punch Co. (Euclid, Ohio), a punch and die supplier for both heavy-gauge stamping markets like construction and smaller-gauge markets like automotive, has to stay apace with its customer base. This has meant shifting from large-volume production to effectively machining smaller runs with shorter turnaround times in order to meet just-in-time delivery orders demanded by its customers’ implementation of lean strategies. As one would expect, adapting to these demands has created its own set of challenges, including finding ways to keep costs down despite the potential for increased labor involvement.

Faced with these issues, production engineer Brian Cain began re-evaluating the company’s manufacturing processes in 2012. A visit to the International Manufacturing Technology Show (IMTS) that year put Mr. Cain in touch with LNS, whose e-Connect system introduced American Punch to the Industrial Internet of Things (IIoT) as well as a way to automate program switches between bar feeder and lathe. 

Coordinate measuring machines (CMMs) have been around since the 1960s. In most precision manufacturing facilities, the CMM is the company’s chief dimensional measurement device that is traceable to the standards maintained by National Institute of Standards & Technology (NIST). Most CMMs are used to verify dimensional accuracy for quality control (QC) and first-article inspection, the function of checking the first part produced by a manufacturing process to verify that it is meeting tolerance requirements. Inspection with a CMM provides data for in-process measurements to ensure dimensional integrity from operation to operation and to satisfy traceability requirements. CMMs are also used to perform gage repeatability and reproducibility (R&R) studies, 2D and 3D scanning, part sorting, reverse engineering and a host of other tasks.

By some estimates, the global installed base of CMMs is about 150,000 units. Because of the typical air-bearing design of many CMMs, the structure of these devices seldom wears out. Therefore, the lifespan of a CMM may exceed 30 years. Many 30-year-old CMMs are used daily throughout the precision manufacturing world. Older CMMs can be easily upgraded with new electronics, drives and the latest software, adding an extra 10 years to a machine’s usable life. In fact, a CMM can be retrofitted multiple times to extend its life even further.

Every motorcycle race team and rider continuously works to improve engine performance. Kieran Sangha, owner of Sangha Race and Restoration in Leicester, UK, builds high-horsepower race-bike engines and knows that simply refurbishing and renewing parts rarely give big performance gains. “Friction between components is an engine and gear killer,” says Mr. Sangha, who, when not transforming motorcycles for racing customers, enjoys the thrill of competition himself. The contact surfaces are under constant stress from powering through the gears while maintaining maximum revs of 18,000 rpm, he says. This causes heat and really dulls performance. It may even lead to component failure and not finishing the rate. Worse yet, a mechanical fault could lead to injury.

Mr. Sangha previously tried to mitigate these problems by vibratory-finishing gears, shafts and engine parts. The process did improve component surface finish to a degree, but they still had a roughness that was noticeably uneven across the surface. Also, chemicals used with the media in the vibratory machines could weaken the metal and hardened surfaces. Disappointingly, component life span and bike performance remained unchanged.

By: Timothy W. Simpson 28. October 2018

Why Is My Surface So Rough?

Designers spend countless hours perfecting the curves and contours of their 3D models in CAD for both aesthetic and functional reasons. Unfortunately, if you have 3D printed anything before, you know that the geometry you print will not be the same as the model you made in CAD. Why is that?

First, most 3D models need to be exported as STL files from their native CAD software in order to be read into build-preparation software such as Materialise Magics and Autodesk Netfabb before additive manufacturing (AM) can take place. During this file export, the 3D model’s edges, contours, curved surfaces and more are approximated by a bunch of triangles in a process called tessellation. So, circles are not perfect circles anymore; they are approximations formed by a series of straight lines—the edges of the triangles used in the tessellation (see Figure 1).

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