ABRASIVES, HONING & FINISHING FINISHING ON A HIGH NOTE It would be lovely to think that components emerge from a mill, lathe, punch press or laser cutter all ready for delivery to the customer. In reality, however, some form of finishing or cleaning is usually required. There are many different reasons for this, but quite often the need for additional processing is driven by customer demands for high levels of surface finish. Indeed, Advanced Grinding Solutions (AGS) says it has received a number of enquiries for lapping machines since being appointed as the sole UK distributor for the FLP range of machines. FLP constructs new single-disc and double-disc machines, and offers rebuilt used machines, often from stock, which have been remanufactured to as-new standard. The company can also supply replacement spare and wear parts for all market-established machines, such as those from Stähli, Wolters, Wenzky, Melchiorre, Lapmaster and Speedfam. It is the rebuild option that seems to have attracted a lot of attention from UK companies looking to update their in-house lapping and fine-grinding capabilities without incurring the costs of purchasing new machines. Many customers choose to acquire rebuilt machines rather than having their own machines overhauled as it means that production is not affected and costs remain more or less the same. Furthermore, customers can always opt at a later date to send old machines to FLP by way of a part-exchange deal. Regardless of the type and size of a customer’s old fine-grinding, flat-honing, lapping or polishing machine – FLP will carry out process and technology orientated improvements and general overhauls. Processes include the replacement of sub-assemblies for which spare parts can no longer be supplied, retrofitting of automation such as PLCs, and the replacement of materials with more wear resistant types, such as rustproof steel. So, what of the precision finishing of cylindrical parts? Well, honing is the historical process of choice, although many are wary of the sometimes high purchase price associated with advanced honing machines. To address the affordability issue, Hurco says that precision honing can now be performed on one of its standard vertical machining centres. Through a partnership with Indiana-based honing specialist Bates Technologies, the solution offers advantages over dedicated honing machines that include reduced investment costs and fewer set-ups. The process is performed on a Hurco VMX series BT40 vertical machining centre as follows. First, a touch probe held in the tool magazine is deployed in the spindle to verify the bore diameter and ensure that the correct program is loaded. The probe then takes another measurement further into the bore to ensure it is straight enough to be machined. Assuming it is straight, the diameter is rough-bored to the correct size for honing. A honing tool with a standard back end is then exchanged automatically into the spindle and throughcoolant is used to activate and control tool expansion, pushing the stones outward while the hone reciprocates and rotates. An in-process air-gauge system enables bore size to be monitored continuously. Once the programmed diameter is achieved, a signal is sent from the air gauge to the Max control of the Hurco machining centre to stop the honing cycle. Finally, the bore is brushed with a soft-finish hone to smooth the high points and provide the required surface finish. Once again, coolant is used to control expansion and pressure. For those with more ‘regular’ finishing requirements, such as deburring for example, vibratory-based machines remain popular. A case in point can be seen at London-based Leon Paul Equipment, a manufacturer of fencing equipment as seen in last year’s Rio Olympics. The sport of fencing demands that foils, epees and sabres are finished to a very high standard. To this end, a focus on deburring and surface treatment has seen two more vibratory machines installed by PDJ Vibro. “Five years ago we started producing a new pistol grip called Evolution for our epees and foils,” explains Jack Jacob, works manager at Leon Paul Equipment, which is based in the Brent Cross area of northwest London. “However, it presented us with the problem of how to achieve the required uniformity of mottling and smoothness on the surface of the aluminium investment castings.” So for the first time at Leon Paul, traditional hand-finishing techniques were replaced with automated de-flashing and surface treatment in a vibratory bowl supplied by PDJ Vibro. Since then, the company has added aluminium guards to the list of parts finished in this way. Sharp edges and flash are removed from the aerospace grade aluminium pressings that form the guards of foils and sabres. Around half of the guards are polished manually to achieve a glossy surface. However, at the end of last year the company decided to look at automation. Again Leon Paul turned to PDJ Vibro and after the successful completion of trials, a second vibratory bowl was delivered along with a supply of small porcelain balls for burnishing the guards and a liquid polishing medium to ensure a bright finish. For the deburring of flat plasma/oxy fuel/laser cut parts, it may be of interest to learn that Ficep UK has been appointed as the exclusive UK agent for Costa Lev machines. Parts up to more than 400mm thick, and more than 3,000mm wide, can be processed at feeding speeds of up to 50m/min. Target application include the removal of slag, burrs and oxide, even when parts are warped or uneven. Once finishing operations are complete, only cleaning/degreasing remains before parts head for the dispatch department. As the final operation, process/machine choice is vital. “Quality comes first without any compromise,” is the ethos of Gamebore Cartridge, a Hull-based manufacturer of shotgun cartridges that contacted MecWash when a new component cleaning system was needed. MecWash recommended the installation of a Duo 400, an aqueous cleaning system which can be applied to even the smallest of parts, such as the diamond shot used in manufacturing Gamebore’s cartridges. “We have been delighted with the quality of cleaning achieved by the Duo 400 because of the pristine finish it offers,” says Phil Plowman, director at Gamebore. “This is vital as any specks of dirt, even the smallest amount, will affect the accuracy and repeatability of the final shot, both of which are critical factors in successful competition shooting.” 12 <strong>Machinery</strong> <strong>World</strong>, <strong>July</strong> <strong>2017</strong>
<strong>Machinery</strong> <strong>World</strong>, <strong>July</strong> <strong>2017</strong> 13