Palletized Production Reduces Lead Times 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 multiplecomponent 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 PROCESS Process 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 CONSOLIDATION In 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 MILLING One 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.” BENEFITS The consolidation of software and machinery has reduced lead times by more than 20%. The ability to automatically convert three-axis to five-axis continuous toolpaths reduces programming time and still enables five-axis machining. Compass technology for feature recognition helps Kellermann to automatically generate two and two-and-ahalf- axis computer numerical control (CNC) programs for regular geometries, which reduces programming time and eliminates potential positioning errors. Error Proofing Your Staff With the right processes in place, human error can be eradicated. Companies have increasingly come to rely on lean manufacturing practices to improve efficiencies in their operations. Yet, without ongoing initiatives, such practices can fall short—particularly in terms of mitigating human error. Human inspection of parts is often not completely effective. Companies are challenged not just to catch the defects caused by mistakes employees make, but to prevent them from occurring in the first place. According to 2010’s Quality Handbook, Sixth Edition: The Complete Guide to Performance Excellence, 100% human inspection of parts is only about 80% effective. The challenge for companies, then, is not to catch the defects caused by mistakes employees make, but rather to prevent them from occurring in the first place. Error proofing, a lean technique used by Donnelly Custom Manufacturing Co. (Alexandria, MN), has proven effective in doing just that. The company specializes in short-run injection molding of complex thermoplastics for industrial original equipment manufacturers (OEMs) who sell end-products in lower unit volumes. Unlike common mistake-proofing techniques that focus on the design phase or the manufacturing processes, Donnelly’s error-proofing methodology focuses on the people, particularly on the mindset needed to implement plant-wide error-proofing techniques. It teaches employees how to take preventative measures that decrease the defects caused by errors. THE WHYS AND HOWS OF ERROR PROOFING Because of the complexity of its business, Donnelly continually seeks out technology advancements and new strategies to improve its productivity and quality. Still, the company faces the inevitable challenges of human error. For that reason, Donnelly chose to apply lessons it learned from the Training Within Industry (TWI) Institute, a program that teaches employees how to improve interoffice relations, problem solving and accuracy. Donnelly created and implemented an error-proofing workshop where employees brought in workplace problems they had encountered that could be addressed with error proofing. Much like TWI, which prepares supervisors to train employees to solve problems, Donnelly’s error proofing teaches employees to be problem identifiers and solvers. The first step in the error-proofing process is to help employees establish the right mindset about making mistakes. Donnelly helped employees understand their own weaknesses by educating them about human behavior. Donnelly shared a 2008 study from researchers at the University of Bergen, Norway and the behavioral neuroscience department at Georgia State University that explains that human error is the result of periodic, minor glitches in the brain. When recording brainwaves, scientists can detect these glitches and accurately predict mistakes up to 30 seconds before they happen. Presenting such material to employees is intended to help them approach the error-proofing process with understanding. When everyone is on the same page, employees must then examine defects caused by mistakes to isolate problems and develop potential solutions. Together, employees brainstorm ideas and rank each potential solution according to the speed, complexity and cost of implementing it, as well as its anticipated effectiveness. Finally, employees evaluate the solutions and provide their cost/ benefit recommendations to customers, who select the one that best meets their needs. Donnelly employees then apply the chosen countermeasure to rectify the mistake. The goal is to determine and select the easiest, lowest cost and most effective solution. Periodic audits help ensure that the countermeasures are effective and enduring. REAL SOLUTIONS, REAL PROBLEMS Donnelly originally established its error-proofing workshop to address quality issues that occurred with one of its longtime customers. Close analysis pointed out a common cause: mistakes due to human error. Applying the new error-proofing process to several of this customer’s jobs reduced parts rejection associated with human error by 75% year-over-year and reduced parts-per-million defect measures by two-thirds. Since then, Donnelly has continued to implement error proofing for other customers in multiple jobs. One recent success involved a mold requiring multiple hand-loaded inserts. Two mistakes were occurring in the process: employees periodically forgot to load inserts into their molds, and they occasionally placed inserts in backwards. Together, a team of employees identified 12 different solutions to the problem and ranked them according to cost, speed of implementation and potential effectiveness. The result? Donnelly, in conjunction with the customer, opted to put sensors in the mold that could detect if the insert was in place and would stop the press if it was absent. While this solution required some investment on the part of the customer, it eliminated the risk of a more costly part failure later. Secondly, to prevent the insert from being placed in the mold backwards, Donnelly designed and built the pickouts to hold the inserts so that they could only be placed into the mold in the correct direction. The company also has implemented periodic audits to ensure the countermeasure is being used properly and to measure the success of the solutions. Thus far, the audits indicate the solution has been 100% effective. While error proofing takes time to implement, the benefits to Donnelly’s productivity and quality are well worth the effort. Error proofing empowers employees to use their knowledge, experience and creativity. At its core value, error proofing encourages employees to do their best and eliminates barriers that may otherwise prevent them from taking pride in the work they do. It also builds a sense of trust, encouraging teamwork and respect. The end result is employees who are more committed and motivated, and make a better quality product. BENEFITS Applying the new error-proofing process to several of its customers’ jobs reduced Donnelly’s parts rejection associated with human error by 75% year-over-year. Donnelly implemented a countermeasure to address inconsistencies in its production process, which audits have revealed to be 100% effective. By using error proofing, Donnelly reduced its parts-per-million defect measures by two-thirds.
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