Case Study: Palletized Production Reduces Lead Times
March 1, 2011
German toolmaker Formenbau Kellermann GmbH (Neumarkt, Germany) reduced lead times by more than 20% after investing in VISI software and installing a palletized production process with a zero-point clamping system.
The company was founded in 1970 by Heinz Kellermann and has become a sought-after partner in the automotive industry, providing single-and multiple-component tools for plastic parts such as intake manifolds, oil modules, air filter housings and cylinder head covers. Having relocated and expanded twice, the company is now run by graduate engineer Sabine Kellermann and currently employs 27 people.
“Pricing pressure, competition from emerging countries and the trend toward ever shorter project terms are challenges that force tool manufacturers to rethink the classical form of single item production,” Kellermann explains. “In toolmaking, flexibility and the use of the latest technology is a must. This basic principle also is applicable to Formenbau Kellermann, where we have invested heavily in machinery and software so [that] we are ready to adapt to changing market conditions.”
The milling and electrical discharge machining (EDM) departments are equipped with two HPM1350 U and HPM 1850 U 5-axis milling centers from Mikron/AgieCharmilles, and one 5-axis Huron EX machine. In addition, there is a Mikron HSM 700 milling machine for electrode production, an AGIE 100 wire EDM machine, three vertical eroding machines (Exeron, Hansen), as well as manually operated machines for additional milling, drilling and grinding operations.
Automation in ProcessProcess automation is a specialty of Formenbau Kellermann and it starts with tool design. Areas which are not directly involved in the design also are standardized to the greatest possible extent. Components such as pressure plates or guides are uniform in all tools. In the case of die centering, only two to three different sizes are used. In addition, there is an in-house company standard for design, as well as a standard component catalog.
The computer automated design/computer automated manufacturing (CAD/CAM) software of choice at Kellerman is VISI from Vero Software (Gloucestershire, England). “As a progressive company, we had already invested much earlier in 3-D,” Kellerman explains. “Prior to our switch to VISI in 2003, we worked with ICEM DDN, a product that had been on the market for many years but could no longer compete with modern systems.”
Feature Recognition Drives CAM ConsolidationIn 2004, the company’s North Carolina department was equipped with VISI machining, where the CAM tasks were shared with PowerMILL from Delcam. However, in 2009 the company switched entirely to VISI for all machining activities. “The advantages of a uniform, consistent CAD/CAM system outweighed the benefits of dual products,” Kellerman notes. “Typically, we deal with short programming times, and feature recognition from native CAD data is an important component of our automation strategy.”
The introduction of compass technology for feature recognition means that Kellermann automatically generates two and two-and-a-half-axis computer numerical control (CNC) programs for regular geometries, including common toolmaking features such as holes or milling grooves. This dramatically reduces programming time and eliminates potential positioning errors.
In principle, only three steps are necessary for CNC plate programming: Start the feature recognition, run the company-specific compass based rules and verify the completed CAM programs. The set up and customization of the Compass rules was performed by VISI distributor Mecadat GmbH (Bavaria, Germany), where on-site assistance was provided to analyze the existing CAM strategies and transfer this knowledge to the rules database.
Three-to Five-Axis Simultaneous MillingOne function that is used intensively at Kellermann is the ability to automatically convert three-axis to five-axis continuous toolpaths. “This enables us to reduce expenditures on programming time and still benefit from the advantages of five-axis machining,” Kellermann says. “For example, the Mikron HOM 1350U allows for an approach angle from 16 degrees to -120 degrees, whereby the distance between spindle and table is only 30 millimeters. This approach is applicable for most geometries and we benefit from better surface finish through the use of shorter, more rigid tooling and reduced vibration.
“Automated and standardized processes also require the efficient supply of information,” Kellermann continues. “The possibility of sharing the tool library from VISI was an important milestone for our automated processes. For example, all tooling databases are available to all users across the network and contain information typically seen in expensive tool-management systems such as toolholders, extensions, collets, cutting tools, including assemblies as well as their individual cutting conditions.”
Reducing Costs with Automation“There is rarely something that we cannot mill and we no longer experience bottlenecks on the CNC machines,” says Kellermann.
The five-axis Mikron machining centers are equipped with a palette system that includes three round tables that can each be loaded with one ton and intelligent zero-point clamping systems, which ensure highly optimized use of the CNC machinery.
Kellermann also recognizes the flexibility advantages of a palletized and zero-point clamping system. “A running process can be interrupted at any time, without losing the zero-point,” she says. “This can be particularly useful in case of urgent repairs, or when spotting surfaces must be quickly re-milled, all which affect lead-time and efficiency.”
Kellermann notes that the consolidation of software and machinery has reduced the company’s lead times by more than 20%. “Those who stand still have no chance in toolmaking over the long-term,” she says. “Automation has reduced our costs now and will continue to do so in the future.”
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