Crankshaft machining with tailor-made inserts from CERATIZIT

Report from the CERATIZIT customer Audi Hungaria. Including interview with customer!

CERATIZIT S. A., Mamer, Luxembourg (headquarters), October 2007.

AUDI HUNGARIA MOTOR Kft. in Györ, Hungary, has 5,500 employees. Here the engines for the brands of the Volkswagen group, Audi, VW, Skoda and Seat are manufactured. In Györ the Audi TT Coupé and Roadster is built, and the Audi A3 Cabriolets will be built there in the future. In 2006 more than 23,500 vehicles and close to two million engines left the plant. This makes Audi Hungaria the second biggest exporter in Hungary. For the machining of crankshafts Audi Hungaria counts on the technology and experience of the carbide expert CERATIZIT.

Audi is synonymous with optimum technical performance and the logo with the four rings. In a few words: Audi ranks as one of the top firms in the automotive world. It therefore makes sense to purchase products at CERATIZIT, the technological leader in the field of carbide for wear parts and cutting tools.

Crankshaft machining at Audi
Györ is situated 45 km from the Austrian border, in Hungary, and numbers 130,000 inhabitants. Since 1994 Audi Hungaria Motor Kft has been located at the periphery of the town. Audi selected this site for various reasons: the logistic connection is very good, within a radius of 50 km there are competitive subcontractors, a hall with a surface of 100,000 sq.m. already existed, and a lot of people in this area speak German very well. Furthermore the technical University of Györ ensures that well-trained engineers and experts are available.

Crankshafts are exposed to enormous forces; their production requires maximum precision
Zoltán Szathmári is in charge of production planning and tool technology in engine production at Audi Hungaria Motor Kft. He works closely together with the CERATIZIT representatives and development specialists. His most important contact on site is Barnabás Deri, the sales manager of CERATIZIT Hungaria.

Szathmári leads us through the impressive production department: high, luminous halls with three extremely long and up-to-the-minute production lines, which are in addition fully automated. At Audi in Hungary it is very clean and one is immediately aware that the employees are proud to work here.

In crankshaft machining Audi Hungaria relies on seven different types of inserts from CERATIZIT: special solutions CERATIZIT developed together with the machine manufacturer GFM. Maximum precision is required. Zoltán Szathmári explains: “The crankshaft is an essential component of the engine. It converts the linear movement into a rotational movement. The component is exposed to enormous forces. We manufacture six different crankshafts. The crankshafts are supplied in forged condition. Before machining, a crankshaft for the 3.0 TDI engine weighs 26 kg, after machining it still weighs as much as 18 kg.“

Interview with Zoltán Szathmári, production planning and tooling technology at Audi Hungaria
Mr Szathmári, what is important in the machining of crankshafts?
Szathmári: “Two thirds of production relate to the 3.0 TDI engine. The crankshafts for this engine are made of 42CrMoS4. Rough machining of this crankshaft represents a difficult task as it consists of a high-tensile material at the limit to soft machining. The hard forging skin virtually ‘eats away’ the tool.”

What does that mean for the tools?
Szathmári: “The blank crankshaft is irregular and shows varying properties and the surface is not homogeneous. This means hard and irregular strain on the insert.”

How long does an insert last?
Szathmári: “When rough machining (rough milling of main bearing and webs) the inserts are mounted on a planetary milling cutter or side and face milling cutter. After around 250 crankshafts the inserts in the milling cutter have to be indexed.

How do you assess the relationship with CERATIZIT?
Szathmári: “We have been working together with CERATIZIT for four years and maintain a very open relationship, there are no secrets. For every new development we are informed precisely about what has been improved. CERATIZIT is in a continuous optimization process and is aware that coming to a standstill is dangerous, because the pressure is high: every year we invite tenders for the inserts, every year there are new test procedures and CERATIZIT has to assert itself. We have been very successful for four years.”

Interview with László Janó, product segment V6, mechanical production department at Audi Hungaria

Mr Janó, how long does the machining of a crankshaft take?
Janó: “There are several ways of looking at this. You could say that at the end of the production line a finished crankshaft comes out every 49 seconds. This is the cycle time of the line. Including the buffers (per line there are 5,700 cranks in the buffers) the flow time for 1,400 parts per day amounts to around six days.”

How important is the role of the tools in this production line?
Janó: “Extremely important. This line is very complex and flexible. The investment for such a line, for instance, is three times as high as for a line for the production of cylinder heads. For such a complex machining method process security has to be very good. In the automated machining chain tool life has to be consistently high. 65% of the costs are tooling costs. The tools also play a very important role.”

What is the proportion of non conforming material?
Janó: “The tolerances for a crankshaft are very close. The entire line is designed for this and is continuously optimized. Quality control is also very intensive. For the 3.0 TDI engine a 100% rupture test is carried out. For me the quality of the final product is important, not so much the share of non conforming material. In the last four years only two crankshafts have been returned to us; this was due to faulty material, not to faulty machining.“

What can a crankshaft withstand?
Janó: “I don’t want to give numbers, but the basic rule is that the crankshaft has to withstand three times as much as the engine.”

[Technical info box]
Patrick Zobl, product manager at CERATIZIT, describes crankshaft machining in detail

Technique for crankshaft machining
? High cutting speeds (up to 260 m/min)
? Planetary milling cutters with diameters ranging from 350mm to 750mm
? Dry machining leading to high temperature stress on the cutting material
? High number of teeth of the planetary milling cutters (40 up to 200 teeth)
? Main bearing and webs are machined at the same time with two planetary milling cutters
? Due to the length and the relatively small diameter of the crankshaft machining stability is low

Requirements with regard to the CERATIZIT inserts
? High resistance to thermal shock
? Consistent quality of the cutting material providing process security at the customer
? Long tool life, therefore low tool changing costs
? Smooth surface thanks to lower frictional heat and wear

Materials used in crankshafts
? Cast iron materials for engines when subject to reduced stress in the engine
? Alloyed steel (Cr, Ni, Mo) with high fatigue strength in engines which are subject to higher stress or to reduce weight

Basic characteristics of CERATIZIT inserts
? Geometry of the insert is mainly defined by the profile of the crankshaft
? CERATIZIT chooses the insert to be applied as well as the geometry of the cutting edge

[Info box about the production steps]
Steps in the production of a crankshaft
a. Preparation
1. Cutting and centring
2. Internal and external profile milling of the pin of the bearing and connection rod bearing pin
3. Turning of the main bearing pins and the end parts
4. Deburring
5. Solid carbide deep hole drilling

b. Hardening (induction hardening)

c. Finishing
1. Hard turning
2. Threading
3. Chain wheel broaching
4. CBN grinding
5. Fluorescent rupture test
6. Dynamic balancing
7. Finishing (polishing and lapping)

d. Quality test

The carbide expert CERATIZIT is synonymous with “hard material matters”
CERATIZIT S. A. – the company resulting from the merger between CERAMETAL and Plansee Tizit in 2002 – is a pioneer and global player in sophisticated hard material solutions. The company operates from Mamer, Luxembourg. In selected industrial sectors the 50% subsidiary of the Plansee group is the world market leader in unique and consistently innovative hard material products for wear protection and cutting tools. In the automotive industry, mechanical engineering, oil industry, medical systems, electronics as well as mould and die making customers benefit from this fact. 400 active patents are owned by CERATIZIT worldwide. In the year 2006 the company had a sales volume of 550 mill. Euros and 4,000 employees.

Before machining a crankshaft for the 3.0 TDI engine weighs 26 kg, after machining it still weighs as much as 18 kg.

An Audi employee dismantling a planetary milling cutter. After around 250 crankshafts the inserts in the milling cutter have to be indexed. AUDI HUNGARIA MOTOR in Györ, Hungary: in 2006 alone more than 23,500 vehicles and close to two million engines left the plant.

László Janó, product segment V6 with a finished Audi crankshaft.

Three highly modern complete automated production lines in the huge 100,000 sq.m. hall.

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