Guyson Manufactures Blast Finishing Equipment

Guyson manufactures industrial blast finishing equipment that is often used for the surface preparation of components prior to physical vapour deposition (PVD) and thermal spray coating. These benefits are brought about by blast etching the component surface, promoting the action of mechanical keying by increasing the surface area, which, in turn, can lead to increased coating bond strength.

The company said that, since the early 1990s, there has been considerable growth in the usage of performance-enhancing coatings that offer hard wear, scratch resistance, heat dissipation and corrosion protection for a variety of components, ranging from chrome bathroom fixtures and door furniture, optical glass, exhaust pipes, compressor blades, medical implants and injection moulds to drill bit and cutting tools. These coatings are said to offer an alterative to the more traditional methods of product surface enhancement such as electroplating and can deliver characteristics such as hardness and wear resistance, improved colour fastness, corrosion resistance and a reduction in tarnishing.

To deliver these component improvements, many manufacturers of high-performance components such as high-speed drills, cutting tools and hobs found that a high level of consistency of the surface topography was essential to facilitate the required enhancements in coating adhesion. For several years, Guyson has been working in conjunction with a number of blue-chip cutting tool companies to achieve a consistent blasted component surface finish that delivers improvements in coating adhesion that, in turn, has led to increases product quality and performance.

To achieve the consistency of surface finish necessary has required the use of automated blast finishing equipment to eliminate the inevitable variations in hand processing, coupled with highly controlled fine media blast finishing, 300 mesh and higher, prior to the hard-wear coating. Guyson offers various levels of automation to component manufacturers. Entry-level automated blast systems, for example, are often based around the single Rotating Spindle Blast (RSB) concept.

Single or multiple small components can be blasted in the Guyson Multiblast RSB single-spindle machine, dependent on fixturing and blast coverage. The spindle rotates at a controlled but adjustable speed and the components are grit blasted by a variable number of Guyson model 400 or 900 guns to suit the component and coverage. Component shape and dimensions dictate whether the guns are specified as static or vertically traversing - up and down the profile of the component. These are set at a correct pre-positioned angle and distance to achieve overall coverage of the target surfaces while they rotate on the spindle under a constant stream of Guyson blast media.

This quickly and efficiently achieves the required surface finish, and finally an automated air wash leaves them in a clean state ready for coating or ultrasonic cleaning. For increasing component volumes, the RXS400 rotating and indexing two-spindle system is frequently chosen; this machine has been designed specifically for the work-cell manufacturing environment. Typically, this type of machine is quick to set up, and the blast parameters can be stored in a menu system for later recall to aid the consistency of product surface topography. These machines are suitable for robot load and unload if required.

For very high production volumes, the Guyson Multiblast RXS900 system is often specified. This blast cabinet is fitted with an indexing rotating turntable that can have six or 12 evenly spaced revolving work spindles, which index through the process area, presenting the components accurately and for a precise amount of time in front of the blast guns. Blasting takes place at two of the spindles, which are positively driven by a toothed belt to ensure an even blast coverage during rotation of the component. The machine can be equipped with variable amounts of either Guyson model 400 or 900 blast guns, mounted on fully adjustable arms.

The components are loaded onto the first spindle, outside of the blast chamber, by hand, pick-and-place or robot devices. The turntable then indexes through the blast chamber and around into an air-wash compartment to remove any residue blast media and finally back to the unload position to be unloaded by hand, pick-and-place or robot. Each of these automated blast options involves the tight control of parameters such as media type and size, blast pressure and gun angles. Enhanced media control via vibrating screen separators and/or cyclone separators provides consistent media sizing for improved surface-finish results.

Surface blast speed and blast nozzle stand-off are other parameters to be controlled. All Guyson Multiblast machines are provided with a human-machine interface (HMI) that simplifies the operation of automated blasting, streamlines access to control functions and enables the password-protected direct entry of dimensional data or processing parameters into the system's programmable logic controller (PLC). The panel can also display control settings, production data and system feedback such as sensor and fault indications or maintenance prompts. Guyson is now able to offer an additional option in automated blasting: robot blasting.

The company offers two options, one with the component manipulated under the blast nozzle and the other with the blast nozzle manipulated around the fixed or rotating component. Robot blasting is said to enable very tight levels of blast control and absolute repeatable coverage, time after time. This option is suitable for components that require a precision finish and validation of that finish, such as medical implants. Cost savings in compressed-air consumption, media wastage and labour can often be made to offset the cost of the robot. A complete automated blast machine installation includes a cyclone media reclamator to separate contaminants and fines from the recirculated media and an efficient cartridge-type dust collector that filters exhaust air to prevent the discharge of particles into the work environment.

Guyson offer numerous media delivery and reclaim system enhancements to meet special separation and dust control requirements. The company is also able, through it range of Kerry ultrasonic cleaning products, to direct its customers towards the most appropriate precision cleaning process to complement the automated blast finishing. Prospective users of Guyson automated blast systems are encouraged to submit sample components for free feasibility testing to the company's development workshop in Skipton, UK.

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