Vehicle corrosion worries rust away

Hey there, time traveller!
This article was published 12/05/2006 (7129 days ago), so information in it may no longer be current.

FOR motorists in years gone by — and for some of us old enough to look back on several decades of driving — rust was a constant problem. Even the best of automobiles were inclined to rust sooner or later — and usually sooner. The fact was that just about since the dawn of automobiles good old paint was the only method of protecting bodywork against corrosion.

Even in the late 1970s, I can remember buying a new Italian car then quite popular in Canada and detecting rust within a year of ownership — and it was bubbling through the roof from the inside! Even cars from Japan were prone to rust in their early years on this continent. Nowadays, Japanese nameplate models are rightly praised for their longevity, durability and quality, but it wasn’t always so.

But recent years have seen remarkable changes in the way automakers rustproof their vehicles — and I don’t mean by building them out of composites or aluminum. Any well-looked-after vehicle will take many years for even slight corrosion to reveal itself — even in areas of the country where winter road salt is ever-present. For people living on the B.C. coast, they’re probably driving vehicles that will be heading for the recycler before any serious corrosion sets in.

At one time it was dealers who took care of rustproofing vehicles. All kinds of fascinating systems — some still available for those who want to be doubly sure — were used to delay the onset of rust on a new car. Many did an excellent job and the better ones even involved drilling holes in rust-prone places and spraying inside cavities with a bitumastic material.

Basically, automakers began to take on the job of ensuring that cars would have a rust-free life back in the late 1980s. According to Ford Motor Co., for example, rust is “a non-issue” with modern vehicles, so much work has been done on what goes on under that snappy paint job.

Ford points out that one of the first major automotive corrosion protection innovations was a paint layer called “anodic electrocoat” that the company introduced back in the 1960s. Application involved applying the electrically charged coating to the unpainted vehicle body in a large tank.

In the late 1970s, automakers began using cathodic electrocoat, and Ford was among the first to make the switch. All Ford’s North American assembly operations were converted to electrocoat by the mid-1980s, and one of the reasons for this was to reduce the environmental impact of materials containing lead.

This process worked well for many years, but automakers are always researching ways to improve body protection and during the 1990s, many of them started looking towards galvanizing to make vehicles ever more corrosion-resistant.

Galvanizing is a process that can be applied to mild steel (as used to make most car bodies), cast iron or steel alloys. The body component to be galvanized is thoroughly cleaned and then dipped in a tank of liquid zinc at 500 degrees C. The process coats the body panel or fabricated assembly of panels with a layer of highly corrosion-resistant zinc. Body panels can also be stamped into shape from sheet stock which has been pre-coated with zinc on one or both sides.

This process makes for a very rust-resistant body component indeed. Just think of all those galvanized steel silos you see on farms these days, standing out year round in all weathers and still staying shiny and serviceable for years. Of course, vehicle bodies are painted on top of the galvanized surface, so protection is even greater and the paint itself is usually topped by a clearcoat.

To make sure everything goes well when prepping a car body for life out in the real world, Ford uses something called “digital preassembly.” Early on in the vehicle’s computer-aided design process, Ford makes a careful study of just where corrosion is likely to occur and where road salt is likely to do its worst. Initially, automakers like Ford were galvanizing only panels where the damage was likely to be done, but nowadays, many automakers galvanize the entire vehicle.

We seem to be reaching a time when rust on our vehicles is something we don’t think too about much any more (don’t tell that to the folks who restore classic automobiles!). But this wasn’t achieved without years of research by some very inventive and creative people at automakers like Ford.

Tony Whitney is an award-winning auto journalist and co-host of the popular TV show Driver’s Seat.

— CanWest News Service