Small Tools have Large Impact on Vehicle Quality at GM


DETROIT– Amid high-tech robots, miles of conveyers and multiple assembly lines, a number of inconspicuous hand-held “tools” and their skilled operators are helping General Motors ensure highest levels of vehicle quality before they leave assembly plants.

Their stature may be small, but their impact to initial and long-term quality is large, as Chevrolet, Cadillac, GMC and Buick prepare to launch 27 new or significantly updated cars, trucks and crossovers this year and in 2014.  Chevrolet alone will launch 13 all new or significantly revised cars, trucks and crossovers in 2013 including the all-new Chevrolet Silverado, Impala, Corvette Stingray and Cruze diesel.  

“Customers probably don’t think about what actually goes into putting a high-quality vehicle on the road, although that’s exactly what they expect in appearance and functionality when they are shopping for a new vehicle, said Mike Ptashnik, Quality manager at GM’s Detroit-Hamtramck Assembly. “These tools may be small, but they are really important in helping us build vehicles that deliver on customer expectations.”

Five of these tools, used in most of GM’s 12 assembly plants in the United States, are:

  • Female ostrich feathers that remove fine exterior dust particles before a vehicle is painted
  • Gap sticks to help ensure uniform body fits
  • Velocity meter gauges that confirm door closing efforts are what customers expect
  • Sniffer gauge that detects refrigerant leaks in the engine compartment
  • Water probe that senses interior moisture

Jay Baron, president and CEO of the Center for Automotive Research in Ann Arbor, also sees small tools making big quality contributions.

“With all the technology that goes into designing and making the car, in the end, it’s the small things that really matter,” said Baron. “If the door gaps are not flush and parallel, or the door squeaks when you open it, or there’s a small fleck in the paint finish, the overall quality of the vehicle may be tainted in the eyes of the consumer.” 

Ostrich Feathers Remove Dust

To ensure long-lasting paint quality, GM plants use female ostrich feathers on each vehicle before the top coat of paint is applied. The paint feathers remove microscopic bits of dust that could affect paint quality.

The pre-paint ostrich feather process resembles a car wash without the water. Ostrich feathers are wrapped around six cylinders, two that roll over each of the vehicle sides and two overhead that clean the fascias, roof, hood and decklid. As a vehicle’s steel body approaches, the cylinders roll over the body front to back to capture fine dust particles prior to the final top coat of paint being applied. Female feathers are softer and last longer than their male counterparts.

The feathers are durable yet delicate enough to prevent scratching. Each feather possesses microscopic fingers, which remove fine dust particles from the body by creating static electricity. As the cylinders of feathers do their job, a high-powered vacuum removes dust residue.

The amount of pressure and feather surface or “crush” applied to each vehicle varies from one-to-three inches depending on model and body part being cleaned. Once a vehicle makes its way through the station, a flashlight is used to inspect for any missed particles.

One ostrich feather has no impact on a vehicle’s paint quality. But combined with thousands of other feathers, they are a critical tool used at GM plants. No birds are harmed in the feather collection process, as they are collected as a part of the bird’s natural shedding process.

Gap Stick Ensures Uniform Body Fits

Employees at GM plants receive hours of training on body panel fit and flushness. To ensure vehicles meet extremely tight tolerances, finger-sized measuring tools called gap sticks are used to validate gaps between body panels are consistent and uniform on the finished vehicle.

Gap sticks, which come in different types and are made of plastic to prevent scratches to a vehicle’s exterior, are used in several areas throughout the build process to measure nearly 50 fits and flushness points across a vehicle’s body from front fascia to hood, decklid to rear fascia, and every point in between.

At Detroit-Hamtramck, highly trained and skilled quality inspectors take gap measurements in about 61 seconds, and document the results at the rate of 45 vehicles inspected per hour. At GM’s Ft. Wayne Assembly Plant where nearly 4,000 employees build the all-new 2014 Chevrolet Silverado and GMC Sierra full-size pickups, each Quality operator averages a minimum of 20 hours of classroom and on-the-job training annually, depending on the complexity of the job task. Ft. Wayne’s Quality Department employs more than 250 people on three shifts who conduct a variety of detailed testing and standardized inspection on each vehicle built.

Velocity Meter Gauges Door Closing Efforts

Once fit and flushness levels are achieved, a door velocity meter is used to measure door-closing effort to ensure that a gentle push is enough to close it.

The door meter is a high-tech tool designed and patented by GM. It attaches to the body by covered magnets. Once in place, on the rear quarter panel to test rear doors and on the rear doors to test the front doors, the doors are opened and closed several times to generate a reading that must meet a required velocity that translates to force (effort).

Sniffer Gauge Ensures Leak-Free Refrigerant System

The robustness of a vehicle’s air conditioning system is verified by a sniffer gauge, a tool composed of a long and flexible rubber prong attached to a base unit that emits a loud screeching noise if unacceptable levels of refrigerant is detected.

Previously, GM used black light tests to perform the check, but those were unreliable. The sniffer gauge prevents false leak alerts due to a dual gas inlet that reliably suppresses any signals caused by other gases present in the atmosphere.

The test takes about two minutes after the vehicle has been running for three to five minutes to get refrigerant flowing through the vehicle. Inspectors insert the wand into all interior outlets and under the hood.  

Leaks are rare and when the sniffer alarm sounds, the issue is addressed in the plant before shipping vehicles to dealers if detected levels of refrigerant exceed customer-based expectations.

Water Probe Helps Keep Interior Moisture Out

To ensure a moisture-free cabin, some vehicles are subjected to an eight-minute, monsoon-like water test. After the comprehensive water test, the vehicle’s interior is evaluated for unseen moisture entering the cabin through the use of a water probe.  

The water probe has two foot-long pins, about the size of knitting needles, which are attached to a gauge whose readout indicates if moisture exists. The flat and thin needles are inserted in various parts of the cabin floor front and rear to generate readings.

As with other tests, GM vehicles rarely require repairs, but when leaks are detected they are addressed before the vehicles are cleared for shipment.