March 2008 Edition

high-speed machining

Four collaborate to produce die & mold high-speed success

Thermo stability. Variable pressures. Coolant monitoring.

For the high-speed machining manufacturing industry, these create infinite possibilities with some clever programming to decrease tool wear and breakage, a die-and-mold operation has found.

The customer's initial specification requirements became an opportunity to improve high-speed machining efficiencies through creative partnerships and effective use of new technologies.

The die-and-mold industry is constantly searching for a balance between tool life, heat generation, and cutting speeds. A die-and-mold operation with 3-D specifications required its Okuma MB-56V be set up for high-speed cooling interface and variable psi pressures. It found a multitude of resources for fine-tuning its high-speed machining processes to save tool wear and maintain increasingly tight tolerances.

Partners in THINC collaborators Okuma, Blum LMT, ChipBLASTER, and Caron Engineering applied creative technologies and programming to enable the operator's spindle psi variable requirements and provide the ability to monitor coolant flow and pressure. but they also pushed the envelope on what the combined technologies could really do — a considerable upgrade ready for plug-and-play compared to the customer's previous standards.

Starting small

When cutters become very small, high pressure becomes a problem. According to Doug Noxell, technical advisor and consultant for Gosiger 3D LLC, the ability to use small cutters and go much faster has to do with the Super-Non-Uniform Rational Basis-Spline functions — or acceleration/deceleration ability that should be standard on all high-speed CNC machines.

"Flexibility is key here," explains Noxell. "For instance, an operator can up the tolerance for roughing operations or tighten it up for a finishing operation. While tightening up may slow the machine a little bit, it is just enough to hold the accuracies to spec."

Originally, the coolant pressure on the high-speed vertical machining center was controlled based on the load on the spindle, which works fine for larger tools. However, when using the smaller tools to follow a 3-D shape, Super-NURBS controls are necessary to feed based on holding accuracies at required tolerances that can be set on the control.

ChipBLASTER, a world-renowned company that leads the high-pressure coolant industry, created a software solution to recognize which tool was currently in the spindle and would vary the pressure requirement according to the tool application. In the past, the ChipBLASTER interface allowed for a solid 1,000psi, through-spindle coolant on every single tool used unless a special-ordered, four-pressure factory pre-set option was purchased. The 200-, 500-, 600-, and 700-psi presets were permanent unless changed by a factory representative.

By reducing the pressure to match the application, the coolant pressure now matches each tool placed into the spindle. Utilizing the application programming interface and the plug and play Ethernet capabilities of the Okuma THINC-OSP control, clever programming yielded positive results. Now an infinite number of modifiable pressures can be set for each individual tool, cutting down the waste of energy on the coolant pump as well as avoiding too much pressure on the tool.

Thermo stability is another important factor to consider in tool life management. In this application, the MB-56V utilized two features: thermo distortion of the head and the spindle, and thermal distortion of the actual machine itself.

"In other words, if the temperature of the room goes up, or when using the ChipBLASTER coolant and the temperature decreases, it monitors and thermally compensates for any inaccuracies that would be there," explains Noxell. "The casting would naturally expand with a rise in temperatures, changing the part dimensionally. There are sensors on the MB-56V machine that actually monitor the temperature of the casting and then compensate for any thermal growth."

Laser automation

Having to stop the spindle to measure or replace broken tools was costing the operation valuable time and money. A Blum laser tool setter was integrated through the MB-56V THINC-OSP control to allow unattended machining and efficient tool management. According to John Sherrick, national sales manager for Blum LNT Inc, the laser tool setter is a multi-functional device ideal for high-speed machining.

"If a tool has a lot of run out, which you would normally have in cavity machining on a three-dimensional application, the laser tool setter can verify that the tool is in a certain concentricity limit," explains Sherrick. "The customer now has the ability to measure corner radiuses of the tool and to determine that multiple inserted cutters are not broken or chipped and can assess and direct tool management. The device also checks the cutting tool's edges so tool breakage can be detected before it becomes a problem — all without operator intervention."

Tools are now measured in-process and include measuring the length of the tool while the tools are rotating at the dynamic operating speed of the spindle. The tool setter measures the smallest of tools to monitor tool breakage, requesting another tool as needed or stopping operations before any damage occurs.

Adaptive control

The Okuma THINC-OSP control offers a graphic interface that can simulate the actual tool path run before it actually runs the tool path on the machine, eliminating errors before a part is even cut. During cutting, valuable information is available in real time from tool wear monitoring and cycle times to loads on the spindle — all easily collected into a spreadsheet such as Microsoft Excel — and then can be sent to a coworker's e-mail for further analysis. This includes data collected from the Blum laser tool setter, bar code scanners or other devices and programs integrated through the control, which features 40 GB of hard drive space and full Ethernet connectivity.

To enhance this capability, Caron Engineering developed an adaptive control application to monitor coolant flow and pressure for this application. The company provides software and engineering products to enhance controls for top CNC manufacturers and manufacturing clients. Working directly with ChipBLASTER and Okuma, national sales manager Mark Munroe explains the next step in the process:

"Add the data collection features of their System Tool Monitoring Adaptive Control product, and the user will now be able to look at historical data to determine tool wear issues. For example, an operator can compare what the coolant pressure and flow levels were when a tool started to draw excessive horsepower and then determine if they are affecting tool wear. Adjustments can then be made to correct tool wear issues as needed."

As a tool's cutting edges deteriorate, Caron Engineering found that horsepower would automatically increase and cause potential problems. The TMAC software now accurately measures and displays true motor horsepower for spindle and/or feed axes, determines when a tool is worn or broken, and directs the machine control to take corrective action before damage can occur to parts and tools. The program protects the CNC machine while providing valuable information about the cutting process, reducing high costs of replacement tooling, lost production and rejected parts by effectively measuring tool wear in real time.

Equipped with new technology and an open mind, the operation was able to enhance its existing equipment with products and applications that cut costs, improved efficiencies and delivered quality results to customers without any special integration software or additional interfacing hardware.

Making the most of the newest technologies available through an open architecture control and using best practices, creativity and partnerships with experts in the industry can open opportunities that will keep a business viable in an ever-changing market.

Okuma
Blum LMT
ChipBLASTER
Caron Engineering

What do you think?
Will the information in this article increase efficiency or save time, money, or effort? Let us know by e-mail from our website at www.ToolingandProduction.com or e-mail the editor at dseeds@nelsonpub.com.