Graphel Carbon Products’ Blog Nationwide

Marc Sanders of Entegris | POCO Materials discusses the Nov. 2019 article “How to EDM Steel and Copper Alloy Simultaneously” (written by Marc and Rob Fothergill) with Graphel’s Ken Dworznik.  The discussion includes polarity, on-time, peak current, material choice, and more, with a focus on getting the best results for your EDM application on both steel and copper alloy.  Also, common questions answered!

Rob Fothergill of Entegris | POCO Materials joins Graphel’s Ken Dworznik to discuss his article “An Added Layer of EDM Knowledge” (Week 9 on the blog) and take listener questions on EDM material selection.

Graphel’s Dave Trinkley and Jaime Portillo join Ken Dworznik to discuss their backgrounds in the industry, adaptions to the challenges of Covid-19, Graphel’s different locations, and the solutions that Graphel offers to EDM customers- solutions such as graphite material consulting/distribution, electrode and tooling packages, and engineering services.  Plus a shout-out to the team!

EROWA’s Tom Swihart joins Graphel’s Ken Dworznik to discuss when/why to use tooling in wire or sinker EDM, and EROWA’s new offerings.

Marc Sanders, EDM Application Specialist at Entegris | POCO Materials, joins Graphel’s Ken Dworznik to discuss the services Entegris POCO can provide to EDM users, the importance of graphite material choice, and answer common EDM application questions.

Jim Norcross of System 3R joins Graphel’s Ken Dworznik to discuss System 3R’s history and tooling abilities, as well as tips for EDM applications.

Rob Fothergill of Entegris | POCO Materials joins Graphel’s Ken Dworznik to discuss the EDM Training available at the Entegris POCO training facility and common graphite application questions.

by Entegris Poco Graphite

Increasing the effectiveness of EDM operations does not come solely with technological improvements in the EDM sinker. This is one of many aspects needing to be considered when working to optimize EDM performance and increase productivity. Other areas of consideration include the type of dielectric fluid, tooling and electrode material used in the EDM applications. One area often overlooked or disregarded is the training required to make the most of the many factors affecting efficient operations.

A competitive company should seriously consider every opportunity to take advantage of technical training being offered by leading suppliers in the industry. This training is often at no charge with the only investment to the company being travel and salary. Even the shortest of training sessions provide the opportunity to recover any costs incurred in a very short time. A case in point includes a company engaged in EDMing – primarily carbide – and experiencing significant electrode wear and slow burn times. The wear and slow burn times demanded an increase in the volume of electrodes produced; therefore, not only adding to material cost, but significantly increased manufacturing costs for machining these electrodes.

The manufacturing cost limited profitability in this application, so the decision was made to send an employee to our EDM technical training session. One of the topics covered in the training included electrode material selection, honing in on the advantages of specific material when EDMing high thermally conductive metals. As it turns out, this company was purchasing the wrong type electrode material for EDMing carbide.

When working with metals of high thermal conductivity, the work-piece absorbs the spark energy almost instantly and limits the effectiveness of the EDM process unless changes are made specific to these type metals. In the case of this example, the electrode material used was a medium grade non-copper impregnated material and was selected primarily on a lower material costs than others available. The student realized during this training that copper impregnated electrode materials exhibit significantly lower electrical resistivity values than a non-copper impregnated material and allows for maximum spark intensity in the EDM cut. This not only increases the metal removal rate, but also allows for reduced electrode wear as well.

Another factor learned during this training session included the need to reduce the on-time to a length approximately equal to when the work metal begins to dissipate the spark energy in the cut. Any longer on-time will only serve to increase wear of the electrode without an effective metal removal rate. Upon the employee’s return, he began to implement the lessons learned during his time at the training. With sample material provided during the training, he began to experience immediate productivity improvements in the EDM. He claims his productivity has increased so much that the company has recovered the cost of the training and much more.

Be sure to contact us for more details on how your company can benefit from attending a training session — with both classroom and laboratory activities for the beginner or the experienced EDM operator — on the products you use in your EDM operations. Look for a program designed to help end users gain a better understanding on how to control the EDM process to achieve predictable results and one that enables you to return with practical information that can immediately be put to use on the shop floor.

FOR MORE INFORMATION

Please call your local distributor to learn what our premium graphite solutions can do for you. Visit poco.entegris.com/distributors for the location nearest you.

Different Types of Milling

There are many different types of tooling, the most common being work holding tools.  Work holding tools include jigs and fixtures; cutting tools for milling and grinding machines; dies for cold forming,  forging and extrusion machines; and welding and inspection fixtures. In this month’s blog, we are going to look at the basics of milling.

Milling is the machining process of using rotary cutters to remove material from a workpiece by advancing the cutter into the workpiece at a certain direction. The cutter may also be held at an angle relative to the axis of the tool.  Milling covers a wide variety of different operations and machines and is one of the most commonly used processes for machining custom parts to precise tolerances.

Milling is a cutting process that uses a milling cutter to remove material from the surface of a workpiece. The milling cutter is a rotary cutting tool, often with multiple cutting points.  The cutter in milling is usually moved perpendicular to its axis so that cutting occurs on the circumference of the cutter. As the milling begins, the cutting edges of the tool repeatedly cut into and exit from the material, shaving off chips from the workpiece with each pass. The cutting action is shear deformation; material is pushed off the workpiece in tiny clumps that hang together to a greater or lesser extent to form chips. This makes metal cutting somewhat different from slicing softer materials with a blade.

The milling process removes material by performing many separate, small cuts. This is accomplished by using a cutter with many teeth, spinning the cutter at high speed, or advancing the material through the cutter slowly; most often it is some combination of these three approaches.

There are two major classes of milling process:

• • Face Milling

In face milling, the cutting action occurs primarily at the end corners of the milling cutter. Face milling is used to cut flat surfaces (faces) into the workpiece, or to cut flat-bottomed cavities.

• • Peripheral Milling

In peripheral milling, the cutting action occurs primarily along the circumference of the cutter, so that the cross section of the milled surface ends up receiving the shape of the cutter. In this case the blades of the cutter can be seen as scooping out material from the work piece. Peripheral milling is well suited to the cutting of deep slots, threads, and gear teeth.

Many of Graphel Carbon Products’ customers find milling graphite to be very messy and damaging to their equipment.  Hence, as our milling supervisor, Jim Hoskins states, “We machine graphite, so you don’t have to.”

There are many different types of tooling, the most common being work holding tools. Work holding tools include jigs and fixtures; cutting tools for milling and grinding machines; dies for cold forming, forging and extrusion machines; and welding and inspection fixtures. In this month’s blog, we are going to look at the basics of grinding.

Grinding, or abrasive machining, is the process of removing metal in the form of minute chips by the action of irregularly shaped abrasive particles. These particles may be in bonded wheels, coated belts, or simply loose.
Grinding wheels are composed of thousands of small abrasive grains held together by a bonding material. Each abrasive grain is a cutting edge. As the grain passes over the work piece it cuts a small chip, leaving a smooth, accurate surface. As each abrasive grain becomes dull, it breaks away from the bonding material.

Types of abrasives

Two types of abrasives are used in grinding wheels: natural and manufactured. Except for diamonds, manufactured abrasives have almost entirely replaced natural abrasive materials. Even natural diamonds have been replaced in some instances by synthetic diamonds.

The manufactured abrasives most commonly used in grinding wheels are aluminum oxide, silicon carbide, cubic boron nitride, and diamond.

Types of bonds

Abrasive grains are held together in a grinding wheel by a bonding material. The bonding material does not cut during grinding operation. Its main function is to hold the grains together with varying degrees of strength. Standard grinding wheel bonds are vitrified, resinoid, silicate, shellac, rubber and metal.

Abrasive grain size

The size of an abrasive grain is important because it influences stock removal rate, chip clearance in the wheel and surface finish obtained.

Grinding wheel grade

The grade of a grinding wheel is a measure of the strength of the bonding material holding the individual grains in the wheel. It is used to indicate the relative hardness of a grinding wheel. Grade or hardness refers to the amount of bonding material used in the wheel, not to the hardness of the abrasive.

Grinding wheel structure

The structure of a grinding wheel refers to the relative spacing of the abrasive grains; it is the wheel’s density. There are fewer abrasive grains in an open-structure wheel than in a closed-structure wheel. A number from 1 to 15 designates the structure of a wheel. The higher the number, the more open the structure will be; and the lower the number, the denser the structure will be.

Wheel Balancing, dressing and truing

All grinding wheels are breakable, and some are extremely fragile. Great care should be taken in handling grinding wheels. New wheels should be closely inspected immediately after receipt to make sure they were not damaged during transit. Grinding wheels should also be inspected prior to being mounted on a machine.