Watch this video for a demo of the hand scraping process, and find a link below to a white paper on the topic.
Hand scraping of mating surfaces on a machine tool enables the surfaces to be flatter, more accurately aligned, longer wearing and freer to glide across one another. No automated or mechanical operation can match these benefits. Machine builder Okuma has issued a white paper detailing the benefits of hand scraping, at technique it applies to all of its machines.
The company contends that hand scraping maintains high levels of CNC machining accuracy and reduces wear and tear, resulting in a long, stable and productive life for the machine. This manual process ensures that tight tolerances are consistently maintained and that precision CNC machining performance is sustained for years, therefore yielding the lowest cost-per-part, the company says.
In a nutshell, the hand-scraping difference accounts for four main benefits.
Accuracy - Scraping is done to align components within millionths of an inch, allowing for consistently-held, tight tolerances.
Flatness - Contact points prevent rocking, add balance when tightening, and allow for true flatness in parts.
Oil Pockets - Oil on the surface allows gliding motion.
Appearance - The finishing touch of scraping is aesthetic. Parts are “design scraped” to achieve an attractive textured finish.
To download a copy of the white paper, click here.
Certain products succeed long enough that the product brand acquires its own cachet apart from the originating company name. In certain circles, Seco’s “Duratomic” is like that. The toughness and wear-resistance of this cutting tool coating have made it successful in steel machining applications such as the one portrayed in this video. When the coating was introduced in 2007, Seco says it represented the first time a coating had been manipulated on the atomic level. And in few days, the company says, Duratomic will be introduced again.
Launching April 1, a complete overhaul to the Duratomic line will improve upon the previous successful coating with new coating technology delivering 20 percent greater life across most of the tool’s applications, including heavy, low-speed turning applications that are commonplace among oilfield manufacturers that have applied this tooling in growing numbers in recent years.
Another important feature to be introduced is “edge intelligence,” the company says. The dark color of Duratomic inserts has made edge wear difficult to see. This has been a challenge in high-volume facilities that change inserts frequently, because inserts with unused edges sometimes get discarded. The new Duratomic addresses this challenge with a multilayer system that the company says makes tool wear easy to visually gage.
Learn more by visiting the Duratomic site, which includes a countdown clock ticking the moments until the line’s relaunch.
During my visit to the Blaine, Minnesota, shop, I picked up on a few tricks it uses to be more effective at machining micro features. Here are a few I cite in the article above:
The shop sometimes starts the creation of square-edge micro-slots by first using a ball end mill to essentially rough out the slot before coming back with a standard end mill to create the sharp corners. This minimizes the load on the standard end mill.
Pecking cycles are used for some micro-drilling operations, and the pecking feed distance depends on the material and hole size. However, Challenge Machine has found that some applications lend themselves to drilling without pecking. This is often the case for polyetheretherketone (PEEK), requiring an adjustment of speeds and feeds to generate the proper chip size per tooth so chips can be evacuated out of the hole.
The shop tries to integrate deburring operations during the machining cycle as much as possible to minimize manual deburring work. If face milling is required after holes are drilled, the shop might slowly run a drill backward down each hole to remove any burrs that milling created.
Challenge Machine also commonly provides micromachining lessons to its customers. For nearly every prototype project, the shop works closely with the customer to offer design-for-manufacturability (DFM) suggestions. For example, a part with a callout for a 0.001-inch tip radius would require the shop to use a 0.002-inch-diameter tool. If the designer can accept a 0.0015-inch tip radius, then the shop can use a cutter with a 0.003-inch diameter to speed the machining process.
If you are one of the many manufacturers seriously considering an investment in additive manufacturing, and if you can make it to northern Florida in a few weeks, then take a look at the Additive Manufacturing Users Group annual conference, returning to Jacksonville April 19-23. The program this year is particularly strong, or at least it seems that way to me, because many speakers in the posted schedule address topics relevant to applying additive manufacturing for industrial production.
The Additive Manufacturing Users Group, or AMUG, is a unique organization. As the name makes clear, it consists of users of additive technology. The group started decades ago as a forum for stereolithography enthusiasts, but as 3D part-making technology advanced, both the scope and the name of the group changed various times. Now, with the maturing of 3D printing for prototyping and the advance of the technology into production, a large number of manufacturing professionals can rightly describe themselves as additive manufacturing users, and this annual conference has grown into a significant additive manufacturing event.
AMUG president Mark Barfoot says one of the challenges of a program involving so many speakers is nailing down a precise schedule, but the version released this week is expected to be final. View the most recently posted agenda here. Register for the conference here.
A center hole that is drilled even slightly off-center can lead to a non-concentric workpiece. If no adjustments are made and the runout is too much, that workpiece ultimately ends up as scrap. While a bad center hole may be only an occasional problem, it can be fairly simple to correct with the use of a compensating live center.
The video above from Riten Industries demonstrates how its Adjusta-Point live center is able to offset a shaft’s deviation by means of external adjusting screws. The adjustment process is similar to indicating a part using a four-jaw chuck, and it takes only a few minutes to bring the shaft back within acceptable grinding standards.