Posted by: Peter Zelinski 29. October 2014

Ensuring Accuracy by Containing Coolant

The word “coolant” is deceptive. Coolant in machining is a heat-transfer device. While the fluid cools the cut by transporting heat away from the work zone, it carries that heat to wherever the coolant then lands.

Toyoda says it engineered its new GE4-i cylindrical grinder in part with attention to the thermal effects that might come from heat transfer via coolant. The machine is seen here at this year’s IMTS, where it debuted. The company says the machine’s redesigned casting contributes to thermal stability by capturing and channeling the coolant that falls from the workzone in order to isolate it from the structure of the machine.

Another feature of the GE4-i is an icon-driven and user-friendly control interface, which is valuable in part as manufacturers adapt to the difficulty of finding skilled labor in grinding. More on that here.

Posted by: Derek Korn 28. October 2014

The Value of a Photo

In my humble opinion, I think the cover photo shown above that I was able to take for our October issue was pretty cool. It punctuates the notion that significant tooling capacity is one necessary part of an effective 24/7 machining process (and this article explains R&G Precision’s efforts in that regard).  

But there was another photo I took, the one below, that also captures a lot in one shot.

It shows the tool crib area located behind R&G’s HMC cell that has an efficient layout enabling operators to quickly prep tools and material for upcoming jobs. This area includes a Zoller Smile 400 presetter, a Rego-Fix benchtop hydraulic press used to insert or remove collets from Rego-Fix Powrgrip toolholders, a saw to machine blanks, and carts to contain all the tools and material needed to load a job into the cell or one of the shop’s stand-alone machining centers. Plus, one of the shop’s machine operators is also a programmer, and his programming station is just outside this shot. This enables him to set up new jobs as well as create CAM programs on the shop floor.

Putting together words and sentences and paragraphs to tell stories like R&G’s is one thing I enjoy, but the challenge of capturing supportive, telling photos during a shop visit is just as fun.

Posted by: Peter Zelinski 27. October 2014

Where Do 3D-Printed Molds Make Sense?

Is it possible to mold a plastic part using mold tooling that is also made of plastic? 3D printing technology provider Stratasys says this is not only possible, but preferable in some cases. These photos show examples of 3D-printed “digital ABS” tooling, which is used for both injection molding and blow molding.

The mold tooling material is produced on a Stratasys Connex 3D printer. This printer digitally creates combination materials by rapidly laying down tiny dots of different materials as it builds the part. To create mold tooling, it combines a heat-resistant plastic with a matrix engineered for high strength. The result is a material that can withstand both the high pressure and high temperature of a molding cycle. The mold tooling material is in fact one of the very strongest materials created on the Connex 3D printer, which is more frequently used to make multi-material prototype parts.

Stratasys sales manager Nadav Sella has been involved in the development of this machine’s application to mold tooling ever since an end user of the machine first hit on the idea of making molds this way nearly 5 years ago. He says the life of one of these digital ABS tools is heavily influenced by both the material being molded and the geometry of the part. On a six-cavity injection mold making ice cream spoons in polypropylene, he says the digital ABS mold delivered 600 spoons. By contrast, for more complex geometries using reinforced nylon, the tool might deliver 20 injected parts. In general, where tooling is needed for low quantities or for an initial run of parts, quickly 3D printing a mold can both save cost and speed the time to market, he says.

There are limitations. He and others within Stratasys have worked through a number of applications of digital ABS molds, and this has allowed them to develop a set of best practices that they share with users. That set of best practices keeps improving as digital ABS tooling is applied to more geometries and materials, he says, but the key is to respect the mechanical and physical properties of the tool. Heat conductivity is not like that of aluminum or tool steel, leading to tool design considerations aimed at avoiding heat concentration. One example concerns gate size and type; point gates, cashew gates and banana gates should be avoided.

Precision is also a consideration. The 3D printer is precise, but not as precise as a CNC machine tool. Thus, it can’t produce molds with the finest features, such as the tight-tolerance details of some electronics-industry molds. Also, to ensure the accuracy needed for precise seating of ejector pins, these holes should be 3D printed undersize, then reamed to achieve an accurate diameter.

“This is a different material,” he says. Established moldmaking professionals are accustomed to molds being made from metal. Compared to this, 3D printed tooling requires slight design and process changes. His advice to potential users is to expect to take some time getting used to what this option can do. However, “for the shop that does 100 molds per year—some in steel and some in aluminum—what if 10 or 20 of those molds could be 3D printed instead?” That portion is realistic, and could amount to considerable savings in cost and time.

Posted by: Mark Albert 24. October 2014

The Joy of CNC Machining

James A. Harvey's new book, “CNC Trade Secrets, A Guide to CNC Machine Shop Practices,” offers great advice and oodles of practical tips and checklists for shop personnel newly introduced to CNC machining. What makes the book readable and appealing is that the author clearly enjoys working with CNC technology.

This book bridges the gap between the skilled manual machinist and the CNC machining technologist. Both should read this book to understand one another better. Shop managers and manufacturing engineers ought to read it, too, to understand how they can work with CNC machinists more effectively.

However, the main purpose (and value) of this book is to ease the transition from conventional machining to CNC operations. Even if the reader made this transition years ago, revisiting this experience will provide refreshing and useful insights into the basics. This type of reader is also bound to find numerous tips or “tricks” that prove handy and beneficial. Of course, machining trainees and apprentices can learn much from this book as well.

It is well-written, well-illustrated and well-organized. In short, it’s a fun and useful book on entry-level CNC.

CNC Trade Secrets is available from Industrial Press Inc. or from Amazon.

Posted by: Peter Zelinski 23. October 2014

Weldon-Flat Tools in a Precision Toolholder

Systems for locking end mills in place within a shrink-fit or hydraulic expansion toolholder, so that there is no danger of the tool pulling out during high-force cuts using a toolholder of this type, often require the shank of the tool to be modified for clamping.

However, there is one standard class of tools that already has a shank modified for clamping: tools with Weldon flats.

Schunk recently introduced a system that makes use of the Weldon flat for clamping during high-force milling with a precision holder. The system, seen here as it was displayed at this year’s IMTS, is based on the company’s Tendo line of hydraulic-expansion toolholders. As seen in this model, a metal sleeve holds the tool, clamping on the Weldon flat. That sleeve then provides the surface for the screw that locks the tool in the holder for the high-force milling typical of aerospace materials such as titanium and Inconel.

« Prev | | Next »

Subscribe to these Related
RSS Blog Feeds

Channel Partners
  • Techspex