Tailor Welded Blanks

Since the mid 1970’s, public concern’s about global warming, energy use, and consumer safety have prompted automakers to make changes in the way they design and produce vehicles. As a result, steel firms who produce parts for the auto-industry have also had to adjust the way they do business. One of the most groundbreaking innovations of the past thirty years has been the introduction of tailor welded steel blanks. The production and use of these customized pieces in the steel and auto industries has reduced production costs, allowed automakers to build lighter and therefore more fuel efficient vehicles, and greatly improved the crash performance of cars.

Tailor welded blanks were originally produced by the German firm ThyssenKrupp Steel AG in 1985. Before the introduction of Tailor Welded Blanks, automobile parts were stamped one by one based on the the different thicknesses and material compositions of each part. The stamped parts were then welded together to create a complete piece. ThyssenKrupp improved this process by laser welding different materials with different thicknesses into a single “blank” piece before stamping. Then, the blank could be stamped into one complete automobile part. This process greatly reduced production costs because it allowed steel makers to stamp complete pieces rather than stamping and then welding together smaller parts to create a complete piece. These new tailor welded blanks also had tremendous benefits for automakers. They greatly improved the structural rigidity of automobile parts, giving cars that had parts stamped from tailor welded blanks better crash test ratings. Improvements in the structural rigidity of parts also meant that parts that had previously been reinforced no longer needed the extra support, reducing the overall weight of vehicles by decreasing the number of parts.

Shortly after ThyssenKrupp Steel’s development of tailor welded blanks, steel producers across the world began to adjust the way they produced parts to meet automakers demand for parts stamped from tailor welded blanks. Today, nearly all major automakers produce cars with parts made from tailor welded blanks, and as a result major steel makers have adapted in to order to maintain business relationships with automakers.

Car door stamped from a tailor welded blank.

Car door stamped from a tailor welded blank.

3 thoughts on “Tailor Welded Blanks

  1. One trivial point: both the old and the new that you compare involve welding pieces. But finished parts have both complex geometries, and variation from piece to piece. So welding things together isn’t always easy, and if you want to do a continuous butt-end weld for strength, it’s very very hard.

    In the old days, when weight didn’t make a difference and crash standards were non-existent, then you’d just use whatever the minimum thickness you needed for the whole piece. It generated scrap, but you were throwing away cheap steel. The limitation was the size / complexity of the finished item, which might require making separate pieces.

    Now when both weight and safety matter, you need much more expensive steel and stronger welds. You get the same price for steel scrap even with a fancy alloy, so the more expensive the steel, the more you want to maximize yield from what is initially a rectangular piece of metal. Doing a continuous weld to join two pieces of steel can give you strength comparable to single unwelded piece and let you you use more of the original steel sheet. If you can overlap a bit, rather than join end-to-end then you can weld both quickly and cheaply, too, unlike a spot robot that has to move from place to place, a good second per spot. (Butt welding is harder, but you can run a plasma torch or laser down a straight track pretty quickly.)

    So for the floor of a car you can use a cheap, thin/light/easy to form steel in the middle, where you need to make the indentations for the transmission and gas tank, and a stronger, harder-to-form, more expensive steel at the edges. Cheap and light offsets the cost of tailoring a blank versus using one large piece, even better if you generate less scrap.

    • This may be a bit of an oversimplification, but is the development of tailor-welded-blanks similar to using a cookie cutter on the edge of multiple pieces of dough and joining them via welds , where previous methods simply stamped out as many as one sheet would allow and threw away the scrap?

      I guess I am just curious if the primary innovation is the ability to reduce scrap by joining multiple pieces, or reduce weight and increase strength by allowing different thicknesses and types of steel to be joined.

      Additionally, how have steel presses had to adapt to stamping pieces with multiple thicknesses and types of steel?

  2. One issue: if you are a steel maker, do you let an independent steel service center make the tailored blanks, or do you do it yourself? I think the answer should be the former if the welding/blanking process is generic. A service center can buy steel from multiple firms for customers in multiple industries and so keep capacity well-utilized. If you as a single steel company does the tailoring, you can only do your own steel and so may not be able to keep your capacity utilization high. Furthermore, it means the car company buying your blanks can’t switch to another steel supplier, and they may be reluctant to put themselves in that position. But if you have a unique steel that isn’t easy to process and that you’re just starting to sell, an independent firm may not be willing to invest. Furthermore, steel service centers may do some application engineering, but likely undertake little or no R&D. However, this is supposition: I only have one data point, so don’t know whether ArcelorMittal is alone among steel companies is doing stuff in-house, or even whether what they do in-house is a large share of the tailored blanking of their steels, or only special products that require unique equipment.

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