Effect
of Tooling Cost on Part Price
Annual production volume has a huge effect on the cost of manufacturing a plastic part, especially in injection molding. Injection molding will be used as an example.
Before an
injection molded part can be made, a mold must be constructed. Molds are usually made from hardened
steel. They vary widely in complexity,
but even molds for simple parts can be very complex (see the section on Injection Mold Types for more information). As a result, they represent a large portion
of the manufacturing cost. A one cavity
mold for a fairly simple part could cost around $20,000 to $30,000. As the number of cavities increases and the
part becomes more complex, molds can easily cost hundreds of thousands of
dollars. For example, a two cavity
three plate mold for a headrest collar piece on a Jeep Wrangler cost about
$125,000.
In many
cases, the cost of the mold is amortized into the piece cost. Lets use the two cavity headrest collar mold
as an example. Projected annual volume
is 30,000 pieces for four years. After
four years, the part will be obsolete.
So, about 120,000 pieces will probably be made from this mold. At an 8% interest rate, with monthly
payments and amortized over four years, the total cost of the mold is
$146,478. If this cost is divided among
all the parts, tooling costs $1.22 per part.
Other factors that influence part cost are material usage, injection
molding machine time, labor, and packaging.
For this particular part, the approximate costs are:
Tooling = $1.22 66%
Material = $0.31 17%
Press Time & Labor = $0.26 14%
Packaging = $0.07 4%
Total = $1.86
Tooling
represents a significant (66%) portion of the total piece cost. Lets say that production volumes are only
10,000 pieces per year. Now the mold
cost is amortized over 40,000 pieces, and represents $3.66 per part. For an extremely low production, of say,
1,000 pieces total, each part will cost about $147 (of course, a one cavity
aluminum mold, which would be much cheaper, would be built if the volume were
only 1000 pieces)!
Injection
molding usually becomes cost effective with volumes around 10,000 pieces. Each situation is unique, however, and high
part cost may be acceptable.
Tooling
cost is highest for injection molding.
Compression and transfer molds are a little cheaper. Blow molds are even less expensive, since it
is a low pressure process and the molds are usually made from aluminum, which
is much easier to machine (also, the parts are usually less complex). Rotational molding, thermoforming, and
extrusion tooling is relatively inexpensive.
Casting tooling cost is minimal, since it is usually used to only make a
few parts.
Click here to download an
Excel Quoting spreadsheet. You can
use this to estimate manufacturing cost of a part.