PCDで最適な深穴加工

Harzgerode工場 で製造されている部品は、アルミダイキャストのクラッチハウジングです。 製造させてました部品は、さまざまな大手自動車メーカーに納入されており、主に 2 リッター エンジンを搭載した車両に搭載されています。 ベルハウジングはトランスミッションをエンジンに接続します。 トランスミッション側はすべてのクラッチ ハウジングで同じですが、もう一方の側は各自動車メーカーのエンジンに適合します。 違いはほとんど小さいため、ベル ハウジングの構造はすべての自動車メーカーで 99% 同一です。

Schlote Harzgerode GmbH社は1 日あたり 4,000 個の部品を生産しています。 現在工場では 80% 以上という非常に高度な自動化が進んでいます。 ハルツゲローデの施設では、120 人の従業員が週 5 日、24 時間体制で働いています。 必要に応じて、生産を週 6 日または 7 日に拡張することができます。

自動車業界全体に言えることですが、部品に対する精度要求は非常に高くなります。 「この部品はアダプターフランジだけでなく、トランスミッションの後部も含まれます。 したがって、ベアリング シートには最高度の精度が必要です」と Schlote社 の作業準備チーム リーダー、Sebastian Swiniarski 氏は説明します。 この部品には公差の異なる多数の穴が必要であるため、1,000 分の 1 ミリメートルの精度で製造する必要があります。

MAPALとSchlote社は、長年にわたる効果的な協力関係を振り返ることができます。MAPALは、PCD フライスカッター (シーリング材を塗布する面の荒面を製造する)、タップドリル、リーマー、多様な穴あけ工具の供給を委託されています。 「当社は、プロセス全体の開発を含む包括的なソリューションをお客様に提供しています」と MAPAL の Schlote 技術顧問、Stefan Frick 氏は述べています。

A watchful eye was kept on the implemented tools from the very beginning. Since Harzgerode went into operation, analyses have been performed continuously to find possible weak points and optimise manufacturing. Within the context of this continuous improvement process, Schlote and MAPAL have together managed to achieve longer tool lives, lower tool expenditures and higher production quantities over years. While 3,600 parts were produced at most per day in the beginning, the limit has now been raised to 4,500 parts – without the need for further machines.

The newest optimisation involves deep drilling for oil channels used to change gears in the automatic transmission. “We evaluate every month with our tool management system which tools have to be exchanged how often”, Swiniarski reports. “Time and again, the deep drills have proven to be particularly sensitive. As these drills are relatively cost intensive, we have concentrated on them to further cut our tool costs.” Quality aspects are also inherent in tool wear as a blunt drill produces burrs at the bore exit.
 

For the new tool, MAPAL started with the existing solid carbide drill and inserted a PCD cutting edge at its tip. The structure of the tool is reminiscent of a concrete drill with a carbide tip. The manufacturers in Harzgerode are very happy with the PCD deep drill’s tool life. While the solid carbide drill’s tool life ends after 2,500 parts, the PCD version keeps going reliably up to 15,000 parts. There is further scope for improvement in machining challenges, such as blowholes in the material and varying casting quality. The partners are currently working on this together. “We have occasionally been able to achieve a tool life of 40,000 parts. Naturally, we want to make this ultra-long tool life the norm”, Frick stresses.

The cutting data is the same as that of the solid carbide drill at a spindle speed of 8,700 rpm, a feed of 0.3 mm/rev and a cutting speed of 218 m/min. The new drill’s potential lays in its considerably longer tool life, the resulting lower tool costs and the higher process reliability. Less tool changes also means less machine downtime.

Production at Schlote in Harzgerode involves a total of ten manufacturing cells. Each cell is made up of three machines from the manufacturer SW, two W06 double-spindle machines and a one6 single-spindle machine. The parts are machined in three clamping setups, whereby the double-spindle machines handle the first two setups and finishing takes place during the third.
 

Clutch housing manufacturing at the site was planned to last at least eight years with a peak output of 1.1 million parts per year. This peak was surpassed in 2020. Production has been ongoing for five years in the meanwhile with 900,000 parts produced per year.

Due to continuously improved productivity and the lower production quantities, there has been time to address future trends and produce different parts. The factory is already being modified for this purpose. The first of two new projects involves six different parts that Schlote is to produce for a hybrid model of super sports car manufacturer.

In the other project, Schlote’s expertise as a clutch housing manufacturer is once again called for – this time for an electric car. Schlote draws from the trend toward electric mobility by supplying e-cars with transmissions as well. For an innovative model with three gears, the connection between engine and transmission is to be produced in Harzgerode. Half of the factory capacity is currently being converted. The production of parts for combustion engines is to be ramped down to 50 per cent. In future, hybrid cars will account for 10 per cent and purely electric mobility for 40 per cent. Schlote has already produced the first parts for the new projects.