Maschinen erfolgreich umrüsten

Im Frühjahr 2011 erhielt Stefan Plätzer die Gelegenheit einen kleinen, aber feinen Maschinenbauer in Eggolsheim zu übernehmen. Zwei Faktoren gaben für ihn den Ausschlag, den Schritt in die Selbständigkeit zu wagen: die allseits anerkannte Zuverlässigkeit des Unternehmens und die ausgezeichnete Qualität der gefertigten Produkte. Stefan Plätzer hat den Metallberuf von der Pike auf gelernt. Zuletzt war er Betriebsleiter bei einem renommierten Automobilzulieferer. Mit seiner eigenen Firma startete er anschließend durch. „Als kleiner Fertiger von Einzelteilen, Klein- und Mittelserien können wir nur auf dem Markt bestehen, wenn wir dauerhaft marktgerechte Preise anbieten können“, sagt er. Wichtig dafür sind die Bearbeitungsprozesse und die Werkzeuge. Zwar bieten viele  Werkzeuge zum Bohren und Fräsen an, aber aus dieser Auswahl das jeweilige Potenzial für die eigene Fertigung auszuloten, dazu fehlen in kleineren Unternehmen oft die zeitlichen und personellen Ressourcen. 
 

Hier kann es sich lohnen, einen starken Partner wie MAPAL mit ins Boot zu holen. Denn die Mitarbeiter von MAPAL haben umfassende Erfahrungen damit, Bearbeitungsprozesse und Spannkonzepte auszulegen und Bearbeitungsmaschinen zu programmieren. Davon profitieren gerade auch kleinere und mittelständische Unternehmen, wie Plätzer: Die Bearbeitungszeit und die Prozesssicherheit für die Herstellung von zwei Robotergreifertypen boten Verbesserungspotenzial. Die Greifer verwendet der Endkunde, um winzige Keramikteile sicher zu fixieren. Nur so können die Teile automatisiert mit einer Schleifscheibe in die vorgeschriebene Form gebracht werden. Entsprechend eng sind die Toleranzvorgaben: Die Abweichung von Parallelität und Rechtwinkligkeit der Flächen ist auf nur 0,02 mm beschränkt.  

“Initially our order was to produce ten pieces of intricate aluminium grippers per month”, explains Stefan Plätzer. “The monthly quantity required then increased to several hundred pieces over time. This could no longer be realised with our previous machining concept.”

This concept was based on the use of conventional carbide drills and milling cutters. Four parts were milled from the solid and finish machined one after the other in three clamping setups. Machining took over one hour. Plätzer therefore had to split manufacturing on two machining centres.

Christian Sandmann, responsible Quality Manager at Plätzer, looks back. “Time and again, we had to make readjustments, make use of additional machine capacities and partly arrange overtime to be able to deliver the ordered amount in good time. This is not acceptable in the long run.”

In this situation, the quality manager remembered his friend, Markus Meyer, who works at MAPAL as a Technical Consultant. At a company visit arranged at short notice, Meyer was presented with the machining process and identified a promising approach for the reduction of the productive time: changing from simple carbide to PCD tools that are characterised by significantly higher feed rates and tool lives.

In an initial step, the MAPAL sales representative suggested the use of two PCD milling cutters. The grippers were milled from solid. This is why the milling proportion and the saving potential for this machining task are high. Stefan Plätzer took up this suggestion. And with great success: Without additional optimisation measures, the machining time for one part was reduced from 15 to two minutes.

“We had stuck with the conventional technology for a long time. The tightly scheduled daily routine left us no room for a far-reaching evaluation of new technology”, remembers Stefan Plätzer. “Since we have had MAPAL by our side, we benefit from the experience and innovation of the company and its employees, among other things. In this way, we can recognise and make use of optimisation potentials much earlier.”

Stefan Plätzer was open-minded when Markus Meyer brought the re.tooling services for the complete gripper production into play, particularly to increase process reliability using new fixture. “For us it was important that the tools as well as the fixture could be used universally as far as possible, as we are primarily active in a segment that is characterised by single piece and small series production”, says Stefan Plätzer.

After the appropriate concept was drawn up in close coordination, MAPAL received the order for its implementation. The service team of the tool specialist undertook all the required work: Starting with the design of the machining process including clamping chuck, the design and organisation of the fixture and the machine programming on site. Specialists from the tool manufacturer also completed the running in of the process.

The result is convincing: Plätzer now manufactures 24 parts in just 48 minutes with a significantly higher degree of precision and process reliability than before. The new fixture contributed significantly to the noticeable improvement in addition to the use of the PCD tools and a custom-made solid carbide step drill from MAPAL. The clamping fixture for the first gripper type has 24 clamping stations and the one for the second gripper type has 36 clamping stations. In addition the number of clamping setups was reduced from three to two.

The time saved is so great that production of both gripper types can be realised on just one machine. Plätzer has thereby gained four weeks of machine capacity for a production quantity of 800 pieces. These are now available for new projects. Stefan Plätzer explains: “If new projects are pending, we consult Markus Meyer if required and clarify whether MAPAL can support us in being able to accept the projects at prices in line with the market. During the consultation, we experienced several times that the sales are not decisive for MAPAL. It is important for the tool manufacturer to make us ready for the future so that we can progress further as partners.”