OPEN MIND CAM System Cuts Lead Times for Mould Manufacturer
The KNARR Group located in Helmbrechts, Germany, is a tool and mould maker that manufactures and supplies standard parts through to complete mould bases to customer requirements. In addition to its modern machine tools, the company uses the hyperMILL CAM system from OPEN MIND Technologies as the basis for the company’s continued business success.
With 20 years experience at a renowned plastics processing company, Rainer Knarr founded his company in 1994. Devoting the business to the manufacture of tools using the knowledge of what tool and mould makers really need, he founded another company in 2000 that set itself the task of selling standard parts – with its own trade catalogue.
The KNARR Group now employs 190 workers at its headquarters in the Upper Franconian town of Helmbrechts. As well as internally produced standard parts KNARR also supplies special versions of these standard parts, as Thomas Wunsiedler, Deputy Marketing Manager, explains: “The expertise and our production equipment make it possible to respond to almost every customers wish.”
KNARR produces parts ranging from ejector technology, guides and tempering elements through to limit switches, centring units, slide elements, short stroke cylinders and collapsible cores. Since 2013, Knarr has also provided mould bases (System K and System F) and P plates of different sizes, designs and materials. In addition to the company’s standard product range, complete machining is also playing an increasingly important role. “The demand for mould bases with customer-specific inclusions is rising constantly,” reports Marco Mergner. As head of department, the engineering technician is responsible for the CAD/CAM programming and milling technology of the department.
Marco Mergner highlights the importance of hyperMILL that: “not only meets our requirements but also plays a decisive role in ensuring that we keep pace and continue to develop.” As the production of mould plates – with a range of special wishes and requirements – is similar to the classic manufacturing of single parts, CAM programming has a key role to play here. “With OPEN MIND’s software, we’re optimally equipped for the future.”
Rainer Knarr and his team of CAD/CAM specialists have placed their confidence and trust in OPEN MIND since the 1990s. Marco Mergner explains: “The considerable technical performance of the individual machining cycles with extensive options for multi-axis and 5-axis machining, deep hole drilling, automation and measurement technology is and remains a decisive factor. Another factor was the user-friendliness of the system plus the excellent service offered by OPEN MIND.”
Today, the KNARR Group has a double-digit number of hyperMILL licences that are used in various departments. Since 2015, the company’s CAM programmers have also been using hyperCAD-S CAD that is based on its own 3D CAD kernel that harmonises perfectly with hyperMILL. Nils Nabor, responsible Area Sales Manager at OPEN MIND, explains: “hyperCAD-S is a CAD system specifically developed for CAM programmers that vastly accelerates NC programming processes. The system helps you to master many of the challenges that arise when working with meshes, faces and solids to create precise components and tools. hyperCAD-S allows you to prepare large volumes of imported data for subsequent NC programming completely independently from the original CAD system that was used for the design process.”
hyperCAD-S – CAD for CAM
CAM programmers perceive hyperCAD-S and the fully integrated hyperMILL as a single entity, whose functions merge into one another, as Marco Mergner explains: “hyperCAD-S and its integrated drawing, face and solid functions allow us to safely carry out all the CAD tasks that are necessary at the start in order to ensure simple and effective programming. hyperCAD-S also offers unique, customer-oriented features for preparing CAD data for subsequent milling with its functions for generating drawings and its use of TAGs. The system is specifically designed to address the requirements of CAM programmers like us. That is quite extraordinary and makes machining so much quicker.”
Employees use hyperMILL to program all the mould plates, which can include complex inclusions and free-form surfaces. The mould plates are often machined completely from six sides in two clamping setups. Special machining operations such as the probing of stock models, deep hole drilling of cooling circuits or the measurement of components after machining can be programmed and generated with hyperMILL just as easily as a simple drilling or milling cycle.
As the components often display certain similarities, Marco Mergner and his team make use of the automation options provided by hyperMILL: “The feature and macro technology allows us to automate many of the programming tasks that repeat. This helps to speeds up the tasks considerably.”
Machining time savings of 90% with MAXX Machining
The hyperMILL MAXX Machining performance package also offers a range of innovative technologies. The power strategies provide a very high level of efficiency in roughing, finishing and drilling. “The way in which OPEN MIND improves and develops its products is exemplary.” Roughing takes place in spiral and trochoidal tool movements. The large axial in-feed depth of the tool over the entire cutting length results in a material removal rate 75% faster than using conventional strategies. This also makes the life of the tools considerably longer.
The 5-axis tangent plane machining and 5-axis tangent machining strategies help reduce machining times even further. These finishing operations make it possible to machine steep, planar and all continuous curve surfaces with conical barrel cutters. Small corner radii can also be milled with the same tool in one job. “These types of operations would take far too long using ball mills and would no longer be economically viable,” explains Marco Mergner. The 5axis helical drilling function is also being used frequently at KNARR and is providing a great benefit. “This function makes it possible to use milling tools tilted in cutting mode to generate various hole diameters, even in materials that are difficult to machine and without the need for any pre-drilling. This means we need fewer tools in the magazine and we save time.”
The machining specialists have demonstrated the significant benefits offered by the tangent machining strategies with conical barrel cutters at a number of events including the ‘Third Knarr Precision Day’, which took place this year. For this purpose, they constructed a 96 mm-thick mould plate with a rectangular, conical breakthrough with a 1mm corner radius. Marco Mergner and his team used all three modules from the hyperMILL MAXX Machining performance package for the complete machining on a 5-axis DMC 80 U duoBlock machining centre from DMG Mori in order to generate the appropriate NC program.
Using 5-axis helical drilling, a milling head first generates the recess. After rouging, the inner surfaces and curved outer surfaces are finished using a conical barrel cutter. “With a conical barrel cutter and 5-axis tangent plane machining, we can select a line spacing of 1 to 2mm and achieve very good surface qualities even with a narrow corner radius. With a 2mm ball mill, we had to choose a spacing of 0.01mm or smaller in order to get a half-decent surface,” explains Marco Mergner.
“In an ideal situation, line-by-line milling with a ball mill would have taken 12 hours. Using the CAM strategy and conical barrel cutter, we are finished in just an hour and can still achieve the very best surface qualities, even in the corners.”