3-flute PHX bull nose end mill eliminates polishing process with enhanced surface quality
Magnus Hoyer | OSG Germany
It is a no-brainer that by employing the latest and greatest machinery, quality and efficiency can be easily achieved. However, not all business can afford the investment, or may be limited by the number of machines they can invest in due to various constraints. When IKO Isidor Kurz Werkzeug- und Formenbau (Tool and Mold Making) was left with a graphite machining center to fulfill a mold order involving work material in 58 HRC that would last for several years, they turned to OSG’s PHX-LN-DBT for process improvement that would enable them to achieve the same result as other high performance machining centers.
IKO Isidor Kurz Tool and Mold Making GmbH & Co. KG is a part of the Kurz Group, which was founded in 1946 by Isidor Kurz. Located in the Owingen district of Haigerloch, Germany, the company is a supplier and manufacturer of customized components and assemblies for the automotive, electronic, medical and consumer goods industries. In addition to the tool and mold making division, the Kurz Group also owns Kurz Kunststoffe GmbH and Kurz Plast Kft., which specialize in the production of sophisticated plastics components.Its tool and mold making division currently employs just over 20 employees. Although small in number, IKO Isidor Kurz Tool and Mold Making takes pride in its products and maintains high quality standards. The company continuously invests in new technology and is always in sync with the manufacturing industry’s changing requirements.
IKO Isidor Kurz Tool and Mold Making gained confidence in OSG’s milling tools through attending one of its workshops on the WXS end mill series for nonferrous materials, mild steels and hardened steels up to 50 HRC. The workshop drew interest of the management team at IKO Isidor Kurz Tool and Mold Making because OSG was able to successfully demonstrate the machining of hardened components on a graphite machining center.
Although graphite machining centers can offer great balance in terms of speed, accuracy and flexibility, its performance is inferior to 5-axis machining centers, especially for the work of deep cavity molds or tall core molds. To compensate, graphite machining centers often have to slow down feed rates to minimize chatter and prevent tool breakage. Achieving the desired quality of surface finish in hardened materials can also present a great challenge.
OSG’s WXS end mills had helped IKO Isidor Kurz Tool and Mold Making increase tool life by a factor of four previously. With this tremendous success, IKO Isidor Kurz Tool and Mold Making decided to consult with their tool distributor and OSG regarding their latest project involvingthe machining of molds in 58 HRC made of a thermoset in which the component must be deformed by force. Due to the nature of the material the mold has to be polished in a very time consuming and costly manner after finishing. At the time, the polishing process required four weeks at an estimate of €3,000 per component. And thus, Klaus Winter, sales representative at the Erich Klingseisen KG, tooling distributor in Aldingen, was confronted with the request to eliminate this expense.
“More specifically, the objective was to reach an Ra value at the surface that reduces the polishing work of the entire contour,” said Winter. “The request is understandable because it concerns a total of six molds and approximately €18,000.”
After a careful evaluation of the application, the sales and engineering department at OSG proposed the PHX-LN-DBT 3-flute long neck bull nose end mill. The PHX-LN-DBT is a long neck bull nose end mill series designed to significantly reduce machine time required for roughing while improving surface quality. Its highly rigid 0.75D short length of cut geometry enables low resistance machining. Without a back taper, the PHX-LN-DBT’s peripheral cutting edge is able to achieve flat milling to improve accuracy in vertical wall milling. Moreover, the PHX-LN-DBT’s strong helix angle ensures that the tool exhibits very low radial deviation to accommodate tight tolerance requirement. Depending on machining environment, the PHX-LN-DBT can completely eliminate the process of semi-roughing and semi-finishing, helping manufacturers drastically improve their bottom line.
IKO Isidor Kurz Tool and Mold Making started off on the mold using a 2-flute cutter for the roughing process. A 2 mm diameter PHX-LN-DBT was then used to produce the mirror surface. The operation finished in a total run time of 22 hours, including six hours for finishing. The PHX-LN-DBT was used for a total of 18 hours, well above average for similar end mills.
“The tool was changed after 18 hours only for safety reasons because it could have lasted longer,” said IKO Isidor Kurz Tool and Mold Making Operations Manager Gerd Kleinmann. “We reached Rz 1.3 µm or Ra 0.16 µm and have thus achieved our goal. Thanks to the PHX-LN-DBT’s third cutting edge, we also achieved measurable time savings.”
A 3-flute end mill with a diameter smaller than 1 mm is hardly available in the market. Thanks to its unique 3-flute geometry, the PHX-LN-DBT can serve as a finishing tool. The cutter not only offers increased surface quality and process reliability, it can also achieve the same cutting speeds or feeds per tooth while the feed rate can be increased by 30 percent when compared with a 2-flute tool.
Traditionally, machining the 58 HRC mold part on a graphite machine center is anything but optimal. It was inevitable due to IKO Isidor Kurz Tool and Mold Making’s circumstance. However, with a change of cutting tool, the burden of the operation was relieved. Contrary to general assertions that very good results can only be achieved with an optimal machining center, the PHX-LN-DBT demonstrates that certain weaknesses can be compensated easily and quickly.