General Engineering A Contractors License # 838691

 An article from PRODUCT FINISHING magazine

Spin Polisher from La Habra Welding

  

Aluminum wheels are big business for both OEMs and the aftermarket. Saving money on polishing without cutting corners on quality is significant.....

 

By Patrick Curran Curran Enterprises Huntington Beach, CA

Rear view of the system shows the media flowing through the wheel as it is dragged along the race track

    A process for preparing OEM and aftermarket aluminum wheels for chrome plating is saving platers and polishers up to $20 per wheel. The process is a simplified drag polisher that pushes four wheels face first through a circular tub of specially designed grinding media (see Fig. 1, 2 and 3). Polishing with media allows for a more controlled and consistent grind that does not cut into the porosity layer below the surface. The process of impacting media against the surface of the wheel causes surface micro-porosity to collapse, significantly eliminating plating rejects. The maintenance of the machine is minimal, and multiple machines can be set up for the price of one standard automated machine with much more capacity.

    As can be seen in Table I, the Spin Polisher TM, manufactured by La Habra Welding (Bell Gardens, CA) has significant advantages over standard processes. This initial capital cost is low for automated equipment, yet the hourly production rate is similar, The process can accomplish approximately 80% of the raw aluminum, >90% of the copper polishing and >90% of stripped wheel polishing, significantly reducing the reject rate for poorly polished wheels and blistering. These estimates are for standard wheel geometries cast via gravity or low-pressure processes.  

    TABLE 1 --Cost and Process Comparison of Major Aluminum Wheel Polishing Methods


  Large Spin Polisher Robotic/Drag Polisher Turntable Polisher Manual Polisher
Production Rate (wheels/hr) 12 16 12 62.5
Capitol Cost $150,000 $1,000,000 $800,000 $--
Cost/Wheel/Hr $12,500 $62,500 $66,667 $--
% Surface Polished 90% 90% 70% 100%
Maintenance Intensity Low High Med Low
Management Intensity Low Med Med High
Safety/Environmental Issues Low Low Low Med
         
As-Cast Polishing Cost $2.50 $6.00 $7.00 $15.00
OEM Copper Buff Cost $0.75 $1.00 $3.00 $5.00
Cost of Poor Polishing Quality $-- $-- $2.00 $4.00
         
Total Polishing Cost Per Wheel $3.25 $7.00 $12.00 $24.00
         
Cost to Polish Stripped Wheel $1.50 $6.00 $7.00 $10.00
Cost of Poor Polishing Quality $-- $-- $9.00 $9.00
         
Total Polish Cost of Stripped Wheel $1.50 $6.00 $16.00 $19.00
         

    The total average polishing costs per wheel can be reduced by approximately 75%. This savings is much greater than the savings per wheel achieved by the other polishing systems. As seen in Table 1 ,both the aluminum and copper polishing costs are reduced significantly. The cost of poor quality, which includes rejects due to polishing mistakes and plating rejects due to embedded compound and porosity is reduced. The aluminum wheels need minor touchup prior to replating. Dayton Alloy Wheel, LLC, is using the system for polishing its copper plated-wheels after a three-year evaluation of the process.

    Wheels that have been stripped undergo almost the same polishing intensity as raw castings. Cutting into the aluminum at this stage causes more problems than with a new casting and generates a high level of rejects after polishing. Because more micro-porosity has been exposed, stripped wheels also have higher reject rates during the plating operation. Typically, about 5O% of wheels that are stripped end up rejected either after repolishing or replating. With this new drag style process, stripped wheels can be polished quickly without removing aluminum. Any surface micro-porosity uncovered during chemical stripping is crushed, and the reject rate after polishing and plating can be reduced by as much as 75%.

    "I use the system to polish all nickel replates, all fully stripped wheels, most copper-plated wheels and most raw casting. The wheels require little touchup and there are few rejects," commented Duane Rogers, plant manager for Perfection Plating (Banning, CA).

    The four head assembly is driven by one motor and gearbox and has no racetrack assembly. The wheel rotation is induced without the aid of a motor. This significantly reduces the initial capital costs and ongoing maintenance costs. Loading and unloading only four wheels per cycle reduces the average wait time per wheel, increasing throughput. As with the racetrack polisher, force grinding by pushing media around and through a wheel is not as geometry sensitive as other automatic grinding processes. Most wheels can be run under the same operating conditions, and the machine can handle 14-22 inch-diameter parts. One operator can run multiple machines.

Article from PRODUCT FINISHING PAGE 2

 

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Copyright 1997 La Habra Welding Inc.
Last modified: December 02, 2009