Precise truck engine cylinder bores

Modern truck engines are produced at the Mercedes-Benz plant in Mannheim, where the requirements for ideal manufacturing include extremely tight tolerances for the decisive dimensions of engine blocks. Thanks to close co-operation between specialists from Mercedes-Benz, the machine manufacturer and Mapal, significant progress was made when a new production line for machining engine blocks was designed and implemented.

The engine blocks have a complex geometry and numerous key characteristics for which the highest tolerance classes must be reliably observed. Depending on the engine type, these include multiple H7 fits, various areas with accuracy specifications less than 15 µm, and chamfers with tight tolerances, including a 20° chamfer with an outlet for which an angle tolerance of just ± 0.025° must be observed.
A first line for machining these engine blocks was commissioned in 2011. When planning a second line, the persons responsible drew on their experience with the first line. The team identified the machining of the bores for the cylinder liner adapters as particularly challenging. Machining was divided into two stations: one for pre-machining and one for fine machining.
To this end, Mapal has developed complex actuating tools that are equipped with up to 20 indexable inserts, including ISO inserts and custom inserts. The actuating tools feature a tool body in monoblock design, and the HSK-160 connection shows an enlarged face surface with a diameter of 200 mm. One tool weighs a total of up to 60 kg.
Despite the connection and a tool length of 380 mm, it must be ensured that the tool has a radial run-out accuracy of 3 µm. The slides are actuated by a drawbar via an additional NC axis in the machine controller that had to be integrated in the HSK connection and suitable for the automatic tool change. This challenge was solved with a high-precision bayonet coupling that is used to couple the drawbar automatically during a tool change.
For further information www.mapal.com

CMM used in novel zero transfer system

Mould maker Kavia Tooling is using a Hexagon co-ordinate measuring machine (CMM) to create an offline zero transfer system ahead of the manufacturing process for parts and electrodes. This strategy considerably reduces downtime on its CNC and EDM machines when setting up new jobs.

Production director Mark Cole says some components are particularly time-consuming to set up traditionally, and even simple parts mean the machines are idle during set up. However, Kavia’s unusual use of the Hexagon CMM means that machines are cutting one job while the set up for the next one is being carried out.
“Hexagon customised their PC-DMIS software, which comes as standard on their measurement devices, to enable us to use it to find offsets at the beginning of the operation,” says Cole. “Instead of having to put each part on the machine and then set it, we set it on the CMM, which gives us the X, Y, Z and U orientation. We only have to put the zero transfer plate, which is micron-accurate, into position on the machine, and it knows the exact location of the part.”
This approach can be done with any number of components, thanks to another piece of customised software that Kavia Tooling devised itself, and which engineers from its CAM system, Edgecam, developed for the company. Edgecam drives seven high-speed CNC milling machines with spindle speeds varying from 12,000 to 30,000 rpm, and a Sodick EDM machine.
“But it’s no ordinary machining process thanks to the customised software which we call Merge,” explains Cole. “It collates data from all programs for the job and merges them into a single file, many at 36 MB and containing around 1.5 million lines of code. Merge also includes the Edgecam NC code, datums to set the parts on, zero transfer, and cutter tool heights.”
He cites an example when the company was working on two cavity plates on one side of the machine, and four inserts on the other: “We put the individual Edgecam CNC programs for each component together into one file, and it all went to the machine as one large program.”

Merge also keeps cutting tools to a minimum, by looking at information such as duplication, length and quality of the tools in all programs.
“If there are two repeating cutting tools in the individually merged program, it selects the best one for the manufacturing process,” says Cole. “It goes through every single NC program and rearranges all the tools accordingly.”
The end result of using Merge with the zero transfer fixture plates created on the CMM is a CNC program which can machine several parts at a time without the need to use the machine as a set-up station, as all preparatory operations are carried out offline.
Says Cole: “If we were setting up a component to be square, directly on the CNC machine tool without the CMM, we’d have to ensure it was perfectly in line with the machine’s axis. Doing that for 10 components considerably increases the risk of error, especially where there are overhangs. In contrast, setting them on the CMM means everything is automatically correct, because it tells the machine the angle of each part.
“To set up six fairly difficult components directly on the machine may take one day, during which time it’s not running,” he adds. “However, it’ll only take about an hour on the CMM, and we can be confident that they’ll all be absolutely accurate.”
Cole says that while the Merge software combines with the CMM zero transfer system to get the best out of the company’s CNC mills, even greater benefits are gained from using it on the Sodick EDM machine.

“This machine used to be our biggest bottleneck,” reveals Cole. “We had to set the electrodes and the part on the machine, and program it by typing-in figures manually, which led to errors. It was an absolute nightmare. However, when we developed the Merge software it went from being the largest bottleneck to the fastest machine in the factory. And it’s all mistake-proof; there’s no typing as everything’s done from the CAD dimensionally. Moreover, all the offsets are set on the CMM so there’s no setting on the machine.”
Merge collates all the programs, zero transfers and information about the spark positioning. The software works with up to 12 electrodes at a time; brings all the CNC programs together; identifies the X, Y, Z and U orientation; puts everything in a format that runs on the Sodick EDM to the correct datum; automatically adjusts the tank height; and provides a setting sheet.
In fact, Merge is proving to be so beneficial for both simplifying and accelerating the work on the Sodick EDM that Kavia is now developing the software commercially for those machines.
“It’s currently being trialled in the field, and we’re aiming to start marketing it shortly,” confirms Cole.
For further information www.edgecam.com

Manufacturers urged to stay open

In an open letter, business and industry secretary Alok Sharma MP (pictured) has stressed the importance of manufacturers remaining open during the current COVID-19 pandemic (while observing safe working practices).

Alok Sharma – UK Parliament official portraits 2017

“Our country needs your support to keep supply chains moving and key workers mobile, as well as to protect the economy as much as possible,” he stated. “Manufacturing is a critical part of our economy and I would like to be clear that there is no restriction on manufacturing continuing under the current rules. Guidelines from Public Health England provide best practice advice on how this can be done safely.”
He added: “I, my fellow ministers and department officials, are in regular contact with industry leaders and trade associations to monitor the effect of COVID-19 on manufacturing and its workforce, and this will carry on. I’m fully committed to continue engaging through the coming days, weeks and beyond to ensure that we can support our manufacturing sector. I realise this will be challenging, but you are contributing to the resilience of our nation and I am grateful for the enormous efforts you are making in order to support the UK at this testing time.”
For further information www.gov.uk

Latest fine-boring tool

A specialist in tooling systems and solutions for the metalworking industries, Big Kaiser, has introduced the latest version of its EWA fine-boring tool.

Available in the UK from Industrial Tooling Corporation (ITC), the intelligent and automatic tool received its global premiere at the EMO 2019 exhibition in Hanover last September. EWA achieves fast, accurate boring because the process does not need to be stopped to make measurements or manual adjustments. As well as saving time, this instils confidence in the operator and minimises costly scrap that can result from manual adjustment errors.
Notable, the EWA’s motor is sealed against dirt and water to IP69 rating. The clamping system provides additional stability and repeatability to deliver consistently high levels of reliability and precision at cutting speeds above 200 m/min.
To maximise flexibility, the tool offers an adjustment range of 22 mm, which ITC says is substantially larger than similar solutions available in the market. Furthermore, the system has an integrated accelerometer that measures vibration during the cutting process and, in the event of excessive vibration, alerts the machine to automatically adjust its cutting parameters.
“The EWA is far ahead of the rest in its level of automation and sophistication, and this gives our customers real benefits in terms of time and money saved,” says Jose Fenollosa, head of R&D at Big Kaiser. “It also makes it ideal for Industry 4.0 applications.
We are talking to potential customers now, including some leading machine-tool manufacturers.”
EWA is initially available in two versions. The EWA Peripheric covers diameters from 68 to 90 mm, while the EWA Centric incorporates a central boring bar with internal coolant for smaller diameters. Further models for different adjustment ranges are currently in the design phase.
For further information www.itc-ltd.co.uk

More appointments at Dugard

The restructuring of the sales division at machine-tool specialist Dugard is now complete, with the company adding six new employees over the past 18 months.

The latest phase in this restructuring programme has seen the company add two more area sales managers. In the southwest and Wales region, Dugard has employed Peter Tilsed, who joins the company alongside Kevin Searl, who will offer sales support to the East Anglia and Home Counties region.
Says managing director Eric Dugard: “We’ve added world-class brands to our portfolio and the sales of these high-quality machines will rest firmly upon the shoulders of our new team. The management team at Dugard are confident that our new sales engineers have the right blend of industry expertise and local market insight to really drive the advantages of the Dugard brand into manufacturing facilities the length and breadth of the UK.”
For further information www.dugard.com