Latest News CITIZEN MACHINING FLEXIBILITY LANDS UNICUT COMPLEX VALVE BODY CONTRACT Go back A special hydraulic valve body contract has been won by Unicut Precision for repeat batches of 2,000 complex multi-featured components due to the company’s capability to re-engineer the production process from an aluminium casting requiring five or six operations into a single turn-mill cycle out of bar. By re-engineering the component that requires 24 tools of which 14 are driven on a Citizen M32-V CNC sliding head auto, the Welwyn Garden City subcontractor eliminated previous process problems experienced by the customer of porosity in the casting, variation in hole and feature positions and possible breakthrough of holes and counterbores in close proximity to each other. Unicut also reduced the likelihood of damage or marking due to the previous method’s requirement for considerable part handling from the number of operations and relocations required. In addition, by using program control, Unicut’s setters were able to precisely deburr critical areas to a consistent standard and maintain sharp corners where specified on the drawing. Said Jason Nicholson joint managing director: “This is a perfect example of how the flexibility of one of our Citizen M32’s can be used to create complicated profiles by extensive interpolation of milling cutters. Also by working from both ends of a component in the main and subspindle we have been able to drill multiple holes with high repeatability to an accuracy of almost true position to the datum.” Each valve body part is 32 mm long and machined from 28 mm diameter bar. There is a complex milled profile on one end and a turned boss and O-ring groove on the other and a 6 mm wide location tenon running down the outside diameter that is blended into the milled profile. This tenon has a long hole drilled 2 mm diameter by 21.5 mm deep that is also counterbored to a 4.00/4.05 diameter tolerance to a depth of 0.70/0.75 mm. This hole is also positioned on a precise 20.60 mm pitch circle diameter (PCD) toleranced to + 0.025 mm. Breaking into this 2 mm through hole at right angles is a feed hole of 1.85/1.90 mm diameter that must be perfectly burr free at the intersection. On the Citizen M32, both these intersecting holes are drilled simultaneously followed by the alternate insertion of two further tools to push over and break the burr before the holes are finally redrilled to final size and blown clear of swarf. Six other holes of small diameter are also drilled and counterbored on the same 20.60 mm PCD with radial tolerances of ± 0.20º from the centre line and to unusual angle positions such as 67.5º and 112.5º achieved by precise indexing of the spindles under program control. One hole is also drilled and tapped M3. The main 10 mm bore into which a bush is later inserted has a tolerance of 15 microns and is counterbored 16 mm to a tolerance of 0.13 mm with 0.6 CLA surface finish. Most edges of the component have to be deburred in-cycle however, sharp corners still have to be maintained on many of the features in order that the sealing and functionality of the component is not jeopardised. Here, along with many of the dimensions, the fact the Unicut Precision has non-contact video-based measuring, combined with touch probe automated inspection, measurement can be carried out very quickly and exactly to a repeatable standard with automated detailed reporting. This facility avoids the need for costly gauges and checking fixtures and eliminates personal ‘feel’, opinion and possible misinterpretation of results. In addition, with the ultrasonic cleaning capability and vacuum drying, using the latest Dürr programmable cleaning system, each part is presented to the customer ready for assembly with the bush inserted and each batch is certified with a quality report.