Page 27 - Metallforming Magazine December 2020

Fabrication: Automotive Blanking Without Stamping Dies
OBJECTIVE
Produce five 12-in.-dia. circles at 113 sq. in. per circle (565 sq. in. for five circles)
TOOLING APPROACH
1-in Stripper Bar* of 5 Circles Results in 1018 sq. in. 1018 - 565 = 453 sq. in. of scrap
LASER APPROACH
Cutting Tangent Arcs of 5 Circles Results in 748 sq. in.
748 - 565 = 183 sq. in. of scrap
45% Scrap
*Stripper bars are required in blanking dies, which limits light nesting.
24% Scrap
Laser blanking allows optimization of blank nesting, which can result in significant material savings.
(Table 3), with savings increasing should production decrease for any reason. Either way, this money can be re-allo- cated to a capital-equipment investment or deployed in part processing.
Potential Material Savings
The combination of software-program advancement and flexibility of laser cut- ting enables nesting and optimizing material usage, to help reduce scrap. Typ- ically, a family of outer-body panels will
consume 14,000 tons of material per year at an average cost of $1600-$1700/ton. Assuming that a stamper receives a scrap credit of 0.10/lb. or $200/ton, then the material cost may total $1400-$1500/ton. Designing blanks to optimize the nesting advantages available through laser cutting can result in an annual savings of 1000 to1500 tons of material. This translates into nearly $2 million/yr. in coil-stock purchasing per year, or $9 million-plus across a
5-yr. program (Table 4).
Other Savings
Although not normally considered a money maker for OEMs, an inventory of replacement body panels must be kept for potential service work. For the part volumes dis- cussed in this example, replacement inventory may include 3000 parts run in the first model year, with a 30-percent volume reduction in each following year. Each replacement- part run requires pulling the die out of storage and recon- ditioning it prior to stamping.
Running service parts with a laser blanking system elim- inates any hard-tooling changeover and only requires a sim- ple change in the software program. Additionally, there is no need to slit master coils to fit service-part dies, because each part made from the master coil can be programmed to run at the master-coil width. This ability helps to minimize coil inventory, as well as the number of different coils used for all of a vehicle’s service parts.
Parts Out the Door
The ongoing argument against laser blanking has been focused on productivity and speed. Yes, a mechanical press only needs a single stroke to cut a blank profile, thus, it has been the technology of choice in high-volume blanking. However, the multi-head laser systems available today can give a stamping press a run for its money.
In a recent study on the time needed to produce 25 parts at volumes of 50,000, we found that a three-head laser system required 1400 hr. to process these parts vs. 1200 hr. using mechanical blanking. So, yes, laser blanking required an additional 200 hr. to run the same number of parts. However, investing in a four-head laser system would certainly meet the
Table 1—Production Volume
Model
Vehicles/Yr.
Blanked Parts/Vehicle
Total Parts
5 yr.
X
50,000
X
25
=
6,250,000
Table 2—Tooling Savings
# of Dies
Cost/Die
Die Cost
Die Maintenance
Total Die Fees
25
X
$195,000
=
$4,875,000
+
$1,706,250
$6,581,250
normally take days to implement using traditional technology can be made for virtually no cost and within 5 min.
Today, the traditional stamping process requires extensive die-production time, with development of the original form- ing-die sets often taking from 6 months to 1 yr. Add to this the tryout and modification time typically required, as well as 14 to 16 weeks to produce the final blanking die after tryout completes, and the process becomes even more
lengthy and expensive.
A Cost-Saving Scenario
Let’s take a look at what coil-fed laser blanking can deliver. According to Auto Trader, the average vehicle model has a lifespan of 4 to 6 yr. To illustrate the savings that can be achieved with this technology, we’ll assume a 5-yr. average model-change scenario, with 25 parts/model and 50,000- unit production volume (Table 1).
Laser blanking, in eliminating the need for dies, offers an immediate savings of more than $6 million (Table 2). This also can be considered as a cost savings of $1.05/part
Table 3—Part Savings
Total Die Fees
Part Total
Die Cost/Part
$6,581,250
÷
6,250,000
=
$1.05
Table 4—Material Savings
Tonnage Savings/Yr.
Cost/ Ton
Total Savings/Yr.
Program Years
Total Sav- ings
1250
X
$1,450
=
$1,812,500
X
5
=
$9,062,500
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