Paint Defect Repair Robot: Wet Sanding to ABB Arms

How the paint defect repair robot grew from wet sandpaper and hand polishing to GM's robotic repair line, and how ABB paint robots and force control could fit.

INDUSTRIAL ROBOTICS

Chat With Robot

10/8/20265 min read

Even in a modern paint shop, some car bodies come out of the oven with a speck of dust, a small run or a crater in the clear coat. For decades a person found each spot under bright lights, sanded it down and polished it back to a shine. A paint defect repair robot does that job with cameras, a sanding tool and close control of pressure. This post traces the work from hand finishing and wet sandpaper to the first paint robots. Then it looks at the systems now running on car lines, where ABB robots could fit, and why the job has been so slow to automate.

Man in work clothes polishing the side door of a dark blue SUV parked on red earth

A worker polishes the freshly sprayed door of an SUV by hand. Photo: Wun-nam Rahimatu / Wikimedia Commons (CC BY-SA 4.0)

How paint shops fixed flaws by hand for a century

Early car bodies were painted in many slow layers, and the finish was rubbed by hand between coats. In 1921 3M released Wetordry, a waterproof sandpaper developed with Francis Okie, an ink maker from Philadelphia. Used with water, it washed the grit away and cut the dust that ruined fresh paint. Later in the same decade DuPont brought out Duco, a quick drying nitrocellulose lacquer made for the car industry, which dried far faster than the old varnishes and shortened the time a body spent waiting between coats.

Worker bending down to polish the lower rear door of a dark blue SUV with yellow bottles beside him

Hand polishing the lower door panel of a car after spraying. Photo: Wun-nam Rahimatu / Wikimedia Commons (CC BY-SA 4.0)

Painting was still long work in the 1940s. A photo from a British car factory in 1945 shows bodies in a spray booth starting what the original caption called a 16 hour journey: three coats of filler, four of primer and two of cellulose, with long drying ovens in between. Any of those layers could trap dirt or sag. Inspectors walked the line looking for flaws, and finishers fixed them one spot at a time with sandpaper, rubbing compound and a polishing wheel.

Black and white factory hall with a car body in a spray booth and more bodies on a track

The paint shop of a British car factory in 1945, where each body got filler, primer and cellulose coats over 16 hours. Photo: Ministry of Information Photo Division / Imperial War Museums via Wikimedia Commons (public domain)

Robots took over the spray gun first. In 1967 Trallfa, a Norwegian wheelbarrow maker, finished a prototype spray painting robot that recorded a skilled painter's movements on magnetic tape and played them back. ASEA, which became part of ABB in 1988, bought a majority of Trallfa's robot business in 1985 and the rest in 1988. As robots did more of the spraying, plants added light tunnels, where rows of bright lamps make dents and dirt easier to see, and later camera systems that scan a body and map its defects. Sanding and polishing the spots they found was still done by hand.

Pale blue jointed robot arm in front of a green sign that reads Painting Robot

A Tokico Armstar painting robot on show at the 1982 World's Fair in Knoxville, Tennessee. Photo: Gary Todd / Wikimedia Commons (CC0)

Paint defect repair robots on car lines today

That manual step is now being automated. In February 2025 3M and General Motors announced that GM was using 3M's Finesse-it Robotic Paint Repair System at its Spring Hill, Tennessee plant, which builds Cadillac SUVs. A vision system checks each vehicle from all angles and sorts the defects it finds, and six axis FANUC robots then sand and polish the spots on a moving line. 3M said it streams data to the robot about every 10 milliseconds so the path can change on the fly. GM called paint repair the final frontier of paint shop automation.

Several white ABB robot arms with hoses around a car body in a bright paint booth

ABB paint robots working on a car body inside a paint booth. Photo: ABB

The robots around that work keep changing too. On 1 October 2026 Dürr launched four EcoRS Generation 2 robots for automotive paint shops, with payloads from 20 to 150 kg and reach up to 3,100 mm, for sealing, cleaning and material handling. Dürr moved the motors for axes three to six, and the cabling, inside the arm, which gives the robot more room around car bodies and makes it easier to clean. With sealing, cleaning and handling covered by robots like these, the repair booth is one of the few places in a paint shop where people still do most of the work.

Open door of a long spray booth with bright ceiling lights and a grated floor

An empty automotive paint booth at a collision repair shop in Chicago. Photo: Scientificranking / Wikimedia Commons (CC BY 4.0)

ABB has worked in paint shops since the Trallfa days. Its IRB 5500 paint robot is built for the explosive air of a booth, and ABB's PixelPaint applies two tone designs without overspray, as our post on car body painting robots explains. For sanding and polishing, ABB's force control software keeps a constant pressure between tool and surface. An IRB 6700 already grinds steel parts this way in Teqram's EasyGrinder cell at Ancofer. The same force controlled arms could, as a possibility, sand and polish paint defects once a vision system tells them where to go.

Row of orange industrial robot arms of different sizes on display in a museum room

ASEA and ABB robots, from the first IRB 6 to the IRB 3000, in the ASEA historical collection in Västerås, Sweden. Photo: Dependability / Wikimedia Commons (CC BY-SA 4.0)

What comes next for robotic paint repair

In car plants, the goal is a closed loop: the camera finds a defect, software decides whether it needs repair, and the robot fixes it with no person in between. The middle step is the hard one, because a flaw that passes on a lower panel may fail on a hood. Inspection systems that use AI to classify defects, like those in our post on AI quality inspection, would feed the repair robot. Repair data could also point back to the booth or oven that caused the flaw in the first place.

Large white ABB robot arm grinding a steel part with sparks flying inside a work cell

An ABB IRB 6700 grinding a steel part in Teqram's EasyGrinder cell at Ancofer. Photo: ABB

Outside the factory, most paint repair still happens in collision shops, where a painter sprays a panel in a booth and polishes it by hand. That is the repair car owners pay for after a scrape in a parking lot. Robots there face a harder problem than on a car line, since every car arrives in a different shape, colour and condition. A small cobot such as ABB's GoFa CRB 15000 could, as a possibility, hold a polisher for a body shop technician, though nobody has shown a product like that yet.

Painter in a face mask crouching to spray a white pickup truck with an open door

A painter sprays primer on a pickup truck in a small body shop. Photo: KelvinJM / Wikimedia Commons (CC BY-SA 4.0)

Cost comes first among the open problems. A repair cell needs cameras, robots, force controlled tools, abrasives and software, and it has to keep up with the line. Sanding pads wear, so the robot must adjust as they do, and a new paint colour or clear coat may need new settings. Plants also need technicians who understand both paint and robots, who can set up force control and test robot paths in simulation before a cell goes live. Those are the same skills behind robot grinding and deburring.

Top view of a white SUV with red and blue patterns on its hood and roof beside a white ABB paint robot

An ABB IRB 5500 paint robot with PixelPaint over Illusorr's finished design on the art car, 2022. Photo: ABB

Innovation

AI solutions for effortless ABB robot control.

Automation

Robotics

ceojohntran@chatwithrobot.net

+84905311611

qtran1215@gmail.com

Instagram