Milling of Electrodes and Mould Inserts Increased productivity: Hard Milling instead of EDMing and polishing
Wild & Küpfer (W&K) produces plastic injection moulded parts that meet high quality standards. The main player is the company's own tool shop, where a Kern Micro and, since 2020, a Kern Micro HD ensure precision and productivity.
“Visions should turn into ideas and then into products”. The Swiss plastic injection moulding manufacturer Wild & Küpfer has followed this credo since it was founded over 40 years ago. The medium-sized company in the canton of St. Gallen offers the complete production chain for products, including logistics and service. It starts with consulting and development. Then it goes all the way to toolmaking and production and to the assembly of parts in the clean room. At the end is logistic, to make sure the parts get to their destination without any damage on time.
This all-in-one solution, together with the highest possible quality, is appreciated by many customers in different industries like electrical and automotive engineering, telecommunications, pharmaceutical, medical and dental technology. Most of them use the entire W&K chain and work closely with the plastics experts right from the development phase.
CTO Daniel Wild, who has been with the company since 2000 and has been managing the company's business with his brother Tobias since 2019, explains: “We produce a wide variety of plastic components and assemblies that our customers need for their end products. The batch sizes average around 100,000 pieces per year. But we also have customers who only need a few 1000 or more than 100 million pieces per year. We can do that too.”
The products are as diverse as the industries. Wild names a few examples: “We produce curtain sliding elements, special bottle caps and electrical connector strips as well as safety-relevant locking systems for the anti-doping area and complex medical-technical assemblies that are used, among other things, for insertion devices for placing stents. This naturally requires a great deal of know-how. ”It starts with the assessment of whether and how the desired plastic parts can be manufactured and ends with the production and delivery of injection-moulded serial parts. The quality standard is always very high, regardless of whether ten thousand or millions of products are required per year.”
80 percent of the quality of a part depend on the tool
Development, construction and production take place between consultation and delivery. In addition, W&K produces all of the moulds for its injection moulding machines itself.
80 percent of the part quality depends on the tool. At this point we don't leave anything to chance, and we don't make any compromises regarding the technical equipment.
The “best quality”-philosophy is nothing new at W&K. Even the founders Tobias Wild sen. (father) and Peter Küpfer (uncle) unconditionally went this way. That brought them together with Kern Microtechnik in 2014. Daniel Wild said: “Back then we were looking for a dynamic five-axis precision machine, also for night shifts without operators, for electrode production that would fit into our automation concept. Of course, the name Kern was very well known in this context. So, there soon was an evaluation and we chose Kern Micro.”
Configured for dry machining of graphite electrodes, it performed this task for many years, 24/7. In 2019 the W&K managing directors had the idea of going into “mixed operation” with a high-precision machine. This means that not only hardened steel, non-ferrous and hard metals, but also wet graphite can be automatically machined on the same machine without any retooling.
The milling of graphite and copper electrodes, hardened mould inserts and carbide parts in small series of an average of 50 pieces has since been taken over by a new top-class five-axis center, as Daniel Wild says: “The increasing volume of orders made a corresponding investment necessary. We evaluated, tested and this time we agreed even faster that we would best solve current and future challenges with the Kern Micro HD.” The Wild brothers are not only convinced by the Kern technology, they also say the same about the philosophy of the company: “It's like ours — you can feel the family spirit. Everyone supports everyone and does not think in the short term, but always in the medium and long term.”
To achieve the best results, Kern engineers adapted the Kern Micro HD perfectly to the needs of W&K. They designed and integrated a special cooling lubricant preparation, a ring nozzle and a large tool magazine with 210 spaces for HSK-E40 holders. This means that mixed operation always works — simple and reliable. Just as helpful in terms of high flexibility: the Kern Micro HD is completely automated with a System 3R cell. In addition, CTO Wild values the many smart components such as the wear-free, actively temperature-controlled linear motors that achieve accelerations of up to two grams and rapid traverse speeds of up to 60 m/min.
Stephan Zeller’s answer to the question of what makes Kern special: „The outstanding technology of this machine has become well known ever since its introduction to the market in 2019 and is very well established among all our customers. A wear-free hydrostatic machine like the Kern Micro HD is really unique on the market.”
Reality: Two hours instead of eight hours
Daniel Wild knows all the features that contribute to the high precision and productivity of the Kern machines. In addition, to get reliable numbers of his own products for his special needs, he carried out his own comparison on a part he frequently needed. It is a round core with an external thread made of carbide. This is required to manufacture a plastic screw cap for a syringe closure in medical technology.
The toolmakers once traditionally produced the round core by sinker EDMing and manual polishing. For comparison, they milled it in five axes with the Kern Micro HD. Wild explains: “We need a good three hours for eroding and then another five hours for polishing. We look at a production time of around eight hours. Milling with the HD takes almost exactly two hours – no operator needed and with a surface which is equal with manual polishing.”
The motto „a machine has to be as flexible as the customer“ is a „must“ for Kern technicians. They upgraded W&K‘s first Kern Micro with a flood cooling unit and a suction unit. Now the Kern Micro stands next to her great sister, the Kern Micro HD and mills highly precise single parts and is needed when a change for parts comes up after production.