Providing submicron accuracy

From small prismatics to rings and casings up to 3.4m in diameter, Manthorpe Engineering specialises in the machining of difficult to manufacture, performance-critical components. It fabricates, machines, tests and assembles high-integrity components from a range of materials, including exotic alloys.

Founded in 1978, Manthorpe Engineering has an extensive site near Derby with over 9,000m² of manufacturing area. The machining division is equipped with the latest high-speed cutting tools on a range of CNC machines, providing 5-axis multitasking capability among a variety of other machining services. These machines are used to turn forgings, castings and a range of other materials into precision-finished components.

“What differentiates us as a company is the complexity of the components that we machine,” begins Manthorpe Engineering’s business director, Tom Pochciol. “They can be large and awkward in shape. We might, for example, be working on the engine casing for a jet or the particularly tight tolerances of a bearing system. A human hair is approximately 60µm in diameter and we regularly have to achieve measurement accuracy to 5µm. Achieving tight positional tolerances are even more challenging. We need a CAD/CAM technology that’s both powerful and flexible.”

Translating customer intent

Manthorpe Engineering uses NX software from product lifecycle management (PLM) specialist, Siemens PLM Software. NX is delivered via TTL a CAD/CAM supplier and Siemens PLM Software partner. TTL customised postprocessors, configured software and delivered user training for the company.

“It’s very important to get the right post-processors for each machine and then fine-tune them,” continues Pochciol. “Our contacts at TTL have been very helpful and continue to provide us with support whenever we need it.”

Customers usually design components and send both 3D and 2D information to Manthorpe Engineering. This kick-starts a collaborative process. “A 3D model is a representation of a perfect idea of what a product should be; yet in the physical world there is variability, so we need to draw on our expertise and knowledge of the customer’s requirements to understand what tolerances are allowed,” comments Pochciol.

The design evolves as Manthorpe Engineering adds specialist expertise to improve manufacturability and shorten timescales.

“One of the first things we do using NX is to ensure we can optimise the design for manufacture,” adds Steve Lee, a manufacturing engineer at Manthorpe Engineering. “Time on the machine is money and if we can find any areas of the design that can be improved, we have a conversation with the customer, interrogate the model in NX and manipulate certain features if necessary. We can iterate with the customer very quickly to ensure the production process is the most cost-effective and time-efficient.”

Lee collaborates with colleagues to plan the manufacturing schedule and programming of machines, which run day and night: “We use information gained from NX to apply times to each toolpath operation. Even at a very early stage, before we have won a contract, we can gain a clear idea of how long a job will take to complete and let our estimators in the sales department know. Once we have actually won a job, we use the information from NX to define the manufacturing method and set up the machining program to select the right tools.”

Positioning curves and flows

Lee adds that the components Manthorpe Engineering receives frequently incorporate smooth, flowing lines involving very complex geometry.

“It would, for example, be impossible to accurately reproduce certain irregular shapes without 3D capability and the manufacturing control that it gives us,” says Lee. “The CAM software I used previously wouldn’t have been able to handle the complexity of the parts we tackle. A key benefit of NX is the ability to keep track of, and graphically represent in 3D, the in-process state of a workpiece relative to the raw material stock. This is critical for effective mill-turning strategies. NX CAM automatically generates an in-process workpiece to provide seamless transfer of workpiece configurations between milling and turning operations.

“The strength of NX is that it’s very easy to compare the model of the raw material prior to machining with the finished product. After the programming of any toolpath, NX gives a visual representation of the material that has been removed and any that is left. This means that we are constantly up to date with the amount of metal the program will remove and also the amount remaining.”

Serving many customers in the aerospace industry, Manthorpe Engineering has a strong quality assurance ethos. Quality processes are thoroughly embedded because the company has to show that it has achieved a target and that it can repeat a methodology. NX is fundamental to this process.

“We provide the NX model to our CMM so that we verify a product against that model,” Lee notes. “The CMM will define the key characteristics of the model and check these in the physical product.”

Training is also very important at Manthorpe Engineering, which is encouraging machinists to learn NX. Lee was a machinist before he began learning CAM and, over the years, has used various software applications: “NX enables complexity yet it is really easy to pick up and a machinist can learn programming very quickly.”

Test accuracy before cutting

NX is the tool that brings planning and production together at Manthorpe Engineering. This is particularly important when the team is handling delicate or expensive materials.

“When we’re working with a tricky material like titanium at a diameter of 3.4m, we cannot afford any mistakes during machining so we run a simulation of the toolpath first,” says Pochciol.

The integrated machine tool simulation is driven by output from the NX postprocessor rather than just toolpath data, so NX facilitates a higher level of program validation. In a virtual environment, NX shows the complete machine, fixtures and tool as it runs through all the movements on the component. That allows both planners and machinists to confirm that there are no clashes, no cuts in the wrong place and minimal waste material.

“An exact fit is very important, particularly when we have valuable parts on a machine,” adds Lee. “NX is the best tool we can have; it gives us complete confidence in the outcome and saves time and money.”

Whether the product measures 6 inches or over 3m, the outcome is attainable because NX handles any differences in size and scale. In addition, it enables effective management of schedules. During a simulation, if the team discovers that a job runs smoothly but not within the anticipated time, there is flexibility to make adjustments.

“NX gives us a full picture of what to expect before a product goes onto the shopfloor,” concludes Lee. “It also provides the reassurance that we are using our machines optimally.”

www.siemens.com/nx