Grinding and Coarse Sanding in the Body Shop
- Always select appropriate Personal Protective Equipment - Eyewear, gloves, hearing and respiratory protection for your job and workplace!
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Once you get a damaged vehicle into the body shop, the first step to take is removal of the trim parts and any parts that prevent easy access to the whole repair area.
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Step 1 - Cutting metal parts
Further cut off any damaged panels or parts.
For cutting metals, 3M offers the Cubitron™ II Cut-off Wheel (available in 75 mm and 115 mm diameter), to be used with 3M Cut-off tool. This allows precise, clean, straight cutting lines and a fast cutting action.
If there are structural components located directly behind the panel to be cut off, it is recommended to use the 3M Cubitron™ II File Belt sander to remove the weld connection point to the panel behind in the damaged part . This helps to avoid any damage of the part behind and thus saves money and time as you don't need specific drills for high strength steel.
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Step 2 - Working with the metal to remove welding lines or spots allowing further removal of damaged parts
3M has identified 3 key abrasive grades that help you to achieve the optimum repair result: P36, P60 and P80. Depending on the size of the repair and the accessibility of the area, you can choose between different types and diameters of abrasive.
a) Use 3M Cubitron™ II Roloc™ Discs (50 or 75 mm) for a fast tool change with the 3M Roloc™ fast connect system. The Roloc™ stud is colour coded to help identifying the right grades.
b) Use 3M Cubitron™ II Fibre Discs (available in 115 mm, 125 mm and 180 mm) to work on larger repair areas, requiring fast action in body repair.
c) Use 3M Cubitron™ II File Belts to optimally open up sanding spots (instead of using a drill bit). Cubitron™ II File belts are available in 3 sizes (10 x 330 mm, 13 x 457 mm and 20 x 520 mm length).
With 3M Cubitron™ II File Belts, you can also easily remove any parts that have been attached by laser welding during the OEM process. "
The next step in the process is to straighten and align the repair area with the new part.
No matter if you weld, braise or bond, you now need to clean the areas to be connected. If bare metal surfaces are required, use one of the following processes to achieve this.
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Step 3 - Paint removal prior to welding or bonding to strip the material down to bare metal in order to repair
For paint and rust removal in the body shop, 3M offers you several solutions depending on which equipment you have available or want to use.
a) Use 3M Bristle Discs on fast turning machines (RPM 8.000 - 18.000 depending on size) to achieve a good, even finish during a fast stripping action.
b) Use Scotch-Brite™ CSD (Cleaning & Stripping Disc) XT for hard substrates with machines of 4.000 - 6.000 RPM. Scotch-Brite™ CSD XT provides fast action and a long life, but leaves a slightly coarser finish.
c) Use Scotch-Brite™ CSD (Cleaning & Stripping Disc) GP (soft) for softer substrates like aluminium with machines of 4.000 - 6.000 RPM. Scotch-Brite™ CSD GP provides fast action and maximum flexibility, leaving a finer finish.
All of these solutions mentioned above are well suited for deburring metals, they leave the steel form intact and minimise scratches to have a clean substrate for welding, braising or bonding.
The following process step is determined by the OEM recommendation.
3M offers solutions for Bonding and support material to improve the Welding process (such as Welding Spark Deflection Paper and Personal Welding Protection Equipment such as the 3M™ Speedglas™ 100V DIN 8-12 face protection mask.)
After you have attached the new part to the car body, flatten the weld lines and weld spots by using again either 3M Cubitron™ II Roloc™ Discs or 3M Cubitron™ II File Belt Sander - depending on accessibility of the area.
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Key for all bodyshop processes is to align the quality requirements between the bodyshop and the paint shop.
A better, targeted work of the body shop allows the paint shop to keep the repair area smaller and thus achieve a faster finish, saving overall time and money. An ideal hand over sanding grade from body to paint shop is P120.
