Taking the rough with the smooth

Anyone of a certain age who served their formative years in a machine shop or sheetmetal shop will know all about deburring. Armed with a file, knocking off burrs or dulling sharp edges didn't seem very important at the time, but, in actual fact, deburring is perhaps the most critical post-machining operation for ensuring the functionality and safe handling of components. Thankfully, it's not the laborious manual task it once was – today, various technologies exist for the reliable automation of deburring operations. DEBURR AT SOURCE Beginning with machined parts, the preferred approach is to deploy cutting tools in combination with programmed routines to ensure components come off the machine burr-free. Among the latest innovations here is a new range of tools from Advanced Carbide Tooling (01455 234000) that combine deburring, corner rounding and chamfering operations. The Nine9 indexable insert corner rounding cutters (www.machinery.co.uk/47069) are based on P35 grade, for cutting speeds up to 350 m/min and feed rates up to 0.1 mm/rev. For more aggressive deburring operations, NCMT (020 8398 4277) last year introduced the Xebec blue fibre aluminium oxide brushes (www.machinery.co.uk/39296). Made from heavy-duty alumina fibres, these tools can be used on machining centres, mills and drilling machines. Xebec tools can be from 6 to 100 mm in diameter and comprise rods consisting of 500 alumina blue fibre filaments, measuring 25 micron diameter. The self-sharpening cutting action is on the tip only, there being no abrasive effect on the sides of the rods. The thicker blue fibres have been added to the existing range of less abrasive white, red and pink fibre Xebec brushes. Moving to profiles and sheet metal components, investment in linishing and deburring technology currently appears high. For instance, Thatcham-based steel profile specialist Procut has recently overcome a bottleneck in its production process using equipment supplied by Surface Technology Products (0121 359 4322). Although the company's four oxy-propane CNC profiling machines were more than capable of meeting the demand of a new long-term order for 2,000 blanks per month, the hard slag that remained on the blanks as a result of the cutting process was a difficult to eradicate. Procut operators were removing the slag by hammer and chisel, or hand-held grinders. The first part of the solution was the acquisition of a belt linishing machine for the cleaning of parts and scale removal. This was followed by a Lima 600L friction deburring machine for removing the hard slag from the cut blanks. "The friction deburrer and linisher from Surtech will pay for themselves in 18 months, such has been the effect on our business," says Procut's general manager, Chris Brown. "As an example of the productivity of the friction deburrer, we have just completed an order of 540 parts – previously, this would have taken a full day to chip away the excess slag. With the friction deburrer, the processing time was just 90 minutes." Another highly successful technology solution can be seen at Eye-based subcontract laser cutting specialist, Wrightform, which is making good use of a recently installed Timesavers rotary brush deburring and finishing system from Ellesco (01202 499400). The Timesavers machine features three main elements: a hard front roller and abrasive belt that removes heavy burrs or surface discrepancies; a set of eight rotary brushes that create a radius on the sheet edge – both outer and inner edges (holes); followed by a softer wheel and fine belt that imparts a grain on the sheet, if required. "The new machine replaces an old Timesavers Grindingmaster machine that only had the capacity for deburring and graining," says Ken Rose, Wrightform's general manager. "The added ability to radius processed sheets is a major benefit and is already a talking point with customers, with one returning all existing stock of laser-cut parts for processing on the new machine." Another way to deburr or improve surface finish is to deploy blasting. Here, Renishaw's recent entry into rapid prototyping technologies has driven the demand for a second Formula 1600 blast cabinet from Guyson International (01756 799911). Both of the Guyson Formula cabinets have been installed to enable Renishaw's R&D department to use blast finishing for the creation of desirable surface textures on laser melted metallic prototypes. The cabinets use the industrial model 400 blast gun, which can be tailored to suit air supplies of between 13 and 27 m³/hr when blasting at 5.5 bar. Also enjoying the benefits of recently installed blasting technology is BAE Systems Surface Ships Ltd, which has increased the production capabilities of its component finishing department with the installation of a high capacity blast cabinet, with custom-built handling features from Hodge Clemco (0114 254 8811). SHIPSHAPE AND BURR-FREE The current workload for the company includes two Queen Elizabeth class aircraft carriers and vessels for the Oman Navy, all of which involve large components. BAE estimates that the savings on subcontractor costs will pay for the new cabinet within 12 months. Inclusion of a track for loading components and an internal turntable for the rotation of parts while they are being blasted has also improved handling procedures and productivity. Finally, for a glimpse of the future, production engineers should look no further than the robot-based deburring area of development targeted by AMRC Manufacturing (AML), a commercial spin-out company from University of Sheffield's AMRC. As part of the European COMET project, AML is developing a robot-based cell (www.machinery.co.uk/41920) that sees an IRB6640/205 robot from ABB (01908 350348), mounted on a fixed base, to deburr components using an Ibag (+46 383 347 30) HF80-S40 spindle capable of 47,000 rpm. The cell has a DropsA (01784 431177) VIP4TOOLS mist lubrication system and employs Delcam (0121 766 5544) Robot Interface software for programming – Delcam is soon to hold a robot machining event (www.machinery.co.uk/48090). Box item 1 of 1 Good vibrations Arguably the most common of all shopfloor deburring equipment is the vibratory finishing machine, known affectionately in machine shop circles as the 'rumbler'. Although mature technology, new models continue to be introduced. A case in point is the recent launch of the VRM125EDSR vibratory finisher from Sharmic Engineering (01299 822135). The VRM125EDSR, with its tri-dimensional action, is suitable for deburring, polishing, burnishing, de-scaling, de-flashing and honing. With a range of machines in the series offering a capacity from 125 to 4,000 litres, they are available as standard or bespoke units that can incorporate an internal separation device, PLC or standard control unit, variable speed, noise cover and compound metering unit. And demand remains high for vibratory finishers. For instance, three new vibratory finishing machines from PDJ Vibro (01908 648757) are helping the Derby facility of Metal Improvement Company (MIC) to streamline the 'CASE' isotropic super-finishing process. CASE uses a combination of controlled shot peening, surface treatment by oxalic acids and non-abrasive vibratory finishing to enhance the fatigue strength and surface properties of components operating under stress. The process is said to be more effective than shot peening alone. The PDJ Vibro finishing machines – an EVT 600 vibratory trough, a JVP 400 centreless bowl and an EVP 550 plain bowl – form an integral part of the CASE process and have been supplied to MIC as part of a 'partnered support' alliance. First published in Machinery, March 2013