01.05.2018
Using new solutions for a reliable process - relief bore is introduced in crancshafts
How an automobile manufacturer brings a new process safely into series production with MAPAL by its side as technology partner.
In cases where completely new machining processes are necessary for common components, innovative technology partners are needed to bring a new process safely into series production. In the course of downsizing, for example, a relief bore is introduced in crankshafts to reduce the weight. To reliably realise this bore through the different bearings in industrial-scale production, MAPAL has developed an appropriate tool concept that is already successfully in use.
To meet the requirements for smaller engines with increasing performance and reduced CO2 emissions, different adjusting screws are turned. In this way, new materials are developed that are lighter but more stable. Or the components of the engine are modified to reduce the rotating mass and in turn the fuel consumption. For example, crankshafts for different engines are
designed with a relief bore. This results in a significant weight reduction for the component.
designed with a relief bore. This results in a significant weight reduction for the component.
A new machining process
For the manufacturing of crankshafts, the relief bore entails an additional machining process. At Daimler AG, the process development, planning and tool management departments work closely together with the manufacturing department for this. However together with the internal parties, suppliers that provide the optimum tools are also needed for reliable machining.
When the process was first designed, tools from different suppliers were considered. To introduce the bore through the bearing of the crankshaft, several manufacturers developed concepts. The solution from MAPAL was convincing. Many employees of the precision tool manufacturer are permanently on site in production in Untertürkheim to fix problems and to
offer support during production. MAPAL has also done a lot of development work and performed trials during the entire time up to latest series. There is often a lack of time for this in mass production and so it is all the more worthwhile for manufacturing companies when a technology partner takes on this work.
offer support during production. MAPAL has also done a lot of development work and performed trials during the entire time up to latest series. There is often a lack of time for this in mass production and so it is all the more worthwhile for manufacturing companies when a technology partner takes on this work.
Burr formation when starting up the series
The four-stage machining process provided the desired results in the trials and series production with a low quantity. However, a problem occurred when starting up series production. A burr formed at the inlet and outlet of the individual bearing bores after around 100 bores that got bigger with each machined bore. The drill heads of the third and fourth drill already had to be changed after 100 bores. This is because the mechanical cleanliness of the
component could not be ensured due to the burr. No metal particles may be found on the component. These could be released when operating the unit. Because of this, any residual dirt and every metal particle on the components must be categorically excluded.
component could not be ensured due to the burr. No metal particles may be found on the component. These could be released when operating the unit. Because of this, any residual dirt and every metal particle on the components must be categorically excluded.
Mass production since September 2017
At the start of 2017, MAPAL tested the new concept in the research and development department with an original crankshaft. “With these results, we could work well and further optimise the tool”; says Moser. The result and speed of the optimisation was impressive.
Things got serious in summer. The modified tool with deburring cutting edge was tested on the machine for series production. The result was also desirable here, and the process including forward and backward deburring of the bores has been used since September 2017 in large-scale production. “Thanks to the deburring cutting edge, the service life of the tools is also much longer than before”, says Tobias Moser. The first two drills are replaced after 2,000
bores and the drill heads of both replaceable head drills after 800 bores. And the deburring cutting edge? It only has to be replaced after 25,000 bores. This means that this process is the new standard for the relief bore of the crankshaft. And it has now been transferred to two other lines.
bores and the drill heads of both replaceable head drills after 800 bores. And the deburring cutting edge? It only has to be replaced after 25,000 bores. This means that this process is the new standard for the relief bore of the crankshaft. And it has now been transferred to two other lines.
Reduce cycle time with the Tritan-Drill
Despite the reliable and satisfactory process, work on improvements and optimisation of the tools is naturally being continued. The first step was to reliably manufacture in large-scale production. Now the task is to make machining even more economical. A first step in this direction has already been taken. “We first used the deburring cutting edge uncoated. Now it
is provided with a special PVD coating for an even longer service life”, explains Tobias Moser. To be able to obtain higher machining values and therefore further reduce the cycle time, the same process is also currently tested on a test machine with counterparts with three cutting edges, different designs of the Tritan-Drill. And the results were very promising, reveals Moser: “If everything goes as expected, we will be able to implement the tools this year.”
is provided with a special PVD coating for an even longer service life”, explains Tobias Moser. To be able to obtain higher machining values and therefore further reduce the cycle time, the same process is also currently tested on a test machine with counterparts with three cutting edges, different designs of the Tritan-Drill. And the results were very promising, reveals Moser: “If everything goes as expected, we will be able to implement the tools this year.”
