Comprising Oxford Engineering, Hutton Precision Engineering and Oxford Engineering Estonia, the Oxford Engineering Group provides a comprehensive range of machining, welding, assembly and testing resources to a global customer base.
Demanding sectors served by the group include the medical, semiconductor, oil and gas, nuclear, and aerospace industries. Due to the exacting precision standards of the components it manufactures and the nature of the challenging materials it machines, such as Inconel and titanium, the Oxford Engineering Group employs a wide range of advanced machine tools, including the two Doosan MX machines recently installed at Bicester-based Hutton Precision Engineering.
To ensure that the new machines produce the required volumes of high-precision parts, an advanced stamping unit, 24 Makro-grip five-axis vices and a wide range of vice jaws were recently purchased from Lang Technik UK.
Hutton’s workshop manager Wayne Bosher says: “The efficient machining of precision parts with less set-ups, fewer machining operations and reduced cycle times was our ultimate aim when we were searching for two CNC turning and milling centres. We found the answer to our needs in a Doosan MX2600ST and a Doosan MX2600.”
He continues: “Although our new Doosan MXs are advanced, high-yield machine tools, as we were aware of the reputation of Lang Technik’s products, we were convinced that the use of the company’s work-holding systems would further improve the productivity levels of our new machines and deliver a range of advantages related to the secure holding of exotic materials when machined under heavy loads.
“Using two advanced Doosan MX machines means that we’ve increased our ability to carry out turning and milling work on complex components, and produce fully finished parts on a single machine. The use of Lang Technik work holding gives us the ability to securely hold workpieces made from the softest of materials, to the hardest, under all machining conditions.”
In addition, Lang Technik’s work-holding solution has increased efficiency levels at Hutton Precision Engineering as its quick set-up times have minimised the downtime of the new multi-tasking machines.
“By the use of our new Lang Technik stamping unit, before inserting a workpiece blank into a Makro-grip five-axis vice, we are able to make precise indentations into it,” says Bosher. “As the projections on the jaws of our new vices engage precisely with the pre-stamped indents, we are able to achieve maximum workpiece holding power with the bonus of only needing to apply minimal clamping forces. Now, as the purpose of our Makro-grip five-axis vices is to simply hold the workpiece with minimum pressure applied, we are able to hold both soft and hard materials without fear of deformation or other problems. The use of the Lang Technik system has improved our process reliability and significantly increased our machining efficiency levels.”
Lang Technik says that its pre-stamping technology, in conjunction with the company’s Makro-Grip five-axis vices, differs fundamentally from the clamping methodologies of other work-holding manufacturers, and has grown to be the benchmark clamping method for secure five-axis machining.
The serrated jaws of conventional vices must fulfil two separate functions; in addition to indenting the workpiece material, they must also securely hold the components. As conventional vices are only able to exert a maximum pressure of approximately 4-6 tons, the effective penetration of their serrated jaws into workpiece materials represents a real challenge, especially when clamping harder materials.
To ensure that the workpiece is penetrated correctly, the teeth of a conventional vice’s serrated jaws must be sharp to remain effective. As these teeth are subject to high levels of wear, their clamping ability is liable to decline. Also, when using conventional vices during the machining of soft, distortion-prone materials, jaw teeth also tend to lose their holding power as they are inclined to work free of the workpiece under machining forces.
The use of Lang’s stamping technology overcomes these problems by applying up to 20 tons of pressure during pre-stamping, ensuring the creation of precise indentations, even when this procedure is carried-out on hard materials of up to 1500 N/mm² tensile strength.
Following pre-stamping, only low clamping pressure is required to hold a workpiece securely as the teeth of the five-axis vice engage precisely with the pre-stamped indents, allowing a relatively compact vice design and the elimination of clamping teeth wear. In addition to securely holding the workpiece in the vice under the most severe machining conditions, the truncated pyramid shapes of the pre-stamped indents prevent clamping teeth from impacting deeper into the workpiece by providing a defined penetration limit.
Lang Technik reports that the use of its pre-stamping technology and Makro-Grip five-axis vices has a major advantage when conventional machine vices reach their limits in terms of material hardness. Despite the application of low clamping pressure, the clamping forces exerted on a workpiece in a Makro-Grip five-axis vice actually become higher in line with the hardness of the component material. Also, as workpieces are prepared outside of the machine tool, less downtime results.
The success of the Lang system means that it has now been rolled out across all of Hutton Precision Engineering’s main milling machines. In addition, Hutton’s sister company Oxford Engineering also uses the Lang system on its medium-sized machines. This strategy helps with the interchangeability of parts between the companies and provides additional capability to respond to flexes in customer demand.
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