CustomPartNet
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August 17, 2026
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Updated August 17, 2026
Deep drawing is one of the more demanding sheet metal operations to tool correctly, and getting the drawing ratio wrong can mean torn parts, wrinkled flanges, or a press that simply isn't strong enough for the job. Before you commit to a design, it helps to know roughly what force the operation will require and whether your material can handle the draw. Once you have that figure, the next step is finding a supplier who has the press tonnage, die experience, and material knowledge to run the part reliably. Browse our supplier network on the right to compare qualified suppliers, review sample parts, and request quotes.
Deep drawing is a sheet metal forming process in which a flat blank is pulled into a die cavity by a punch, producing a hollow, cup-shaped or box-shaped part in one continuous stroke. Unlike bending, which creates a fold along a single axis, deep drawing reshapes the material in multiple directions at once, radially drawing the blank inward as it moves into the die.
The process typically involves a punch, a die, and a blank holder. The blank holder applies pressure around the edge of the blank to control how the material flows into the die, preventing wrinkling while still allowing enough movement to avoid tearing. Getting that balance right, along with selecting the correct blank size, is what separates a successful deep draw from a scrapped part.
Deep drawing is closely related to the bending operations covered in earlier posts in this series, including V-bending and wipe bending, but it puts significantly more strain on the material because the blank is stretched and compressed simultaneously rather than folded along one line.
CustomPartNet's Deep Drawing Force calculator estimates the force needed to complete a draw based on three inputs: the drawing ratio, the sheet thickness, and the ultimate tensile strength of the material.
Drawing ratio (DR) describes how severe the draw is. It's calculated as the initial blank diameter divided by the punch diameter. A higher drawing ratio means more material is being pulled into a smaller opening, which increases the risk of tearing.
Limiting drawing ratio (LDR) is a property of the material itself. It represents the largest blank diameter that can be completely drawn over a given punch without failure. Every material has a different LDR depending on its formability and ductility. If your drawing ratio exceeds the material's LDR, the part can't be formed in a single draw and will need to be completed in multiple stages, called redraws.
Percent reduction is another way of expressing the severity of the draw. It's the percentage decrease from the blank diameter to the punch diameter and is often easier to visualize than the drawing ratio when comparing different part geometries.
The calculator combines these factors with the sheet thickness and the material's ultimate tensile strength to output the tonnage required, which is the number you'll need when specifying a press or evaluating whether a supplier's equipment is a match for the job.
Say you're designing a round steel enclosure with a punch diameter of 4 inches and a blank diameter of 7.5 inches, giving a drawing ratio of 1.875. The material is 18 gauge mild steel, roughly 0.048 inches thick, with an ultimate tensile strength around 45,000 psi.
Using the standard approximation for deep drawing force:
F = π × Dp × t × UTS × (DR − 0.7)
Plugging in the numbers:
F = π × 4 in × 0.048 in × 45,000 psi × (1.875 − 0.7)
F = π × 4 × 0.048 × 45,000 × 1.175
F ≈ 31,900 lbf, or about 16 tons
That figure tells you the minimum press capacity needed for the operation, before accounting for blank holder force, friction, and any safety margin the supplier's tooling engineer builds in. The percent reduction for this part works out to about 47 percent, and since mild steel typically has an LDR in the 2.0 to 2.2 range, a drawing ratio of 1.875 is comfortably within a single draw operation rather than requiring a redraw.
Deep drawing shows up anywhere a manufacturer needs a seamless, one-piece hollow shape rather than an assembly of welded or fastened components:
Kitchen sinks and cookware
Beverage and food cans
Automotive fuel tanks and fluid reservoirs
Electrical and electronic enclosures
Ammunition casings
Appliance housings and drums
Automotive body panels with deep contours
Drawing ratio is the single biggest predictor of whether a part can be formed without tearing. A ratio that's too high relative to the material's limiting drawing ratio means the blank is being asked to stretch more than it can handle in one pass, which typically shows up as cracking near the punch radius.
The part will need to be formed in multiple draw stages instead of one. Each redraw reduces the diameter further using a smaller punch and die, gradually working the material down to final dimensions without exceeding its formability limit at any single stage.
Not necessarily on its own. Force tells you what press capacity you need, but formability risk depends more on the drawing ratio and the material's ductility. A part can require high tonnage without being close to tearing, or the reverse, so both numbers matter together.
Yes. As long as you have the sheet thickness and the ultimate tensile strength for your material, whether that's aluminum, stainless steel, copper, or another drawable metal, the calculator applies. Just keep in mind that LDR values vary significantly by material and temper.
Thicker material increases the force needed roughly in proportion to thickness, since more material is being sheared and stretched at the punch radius. Thicker stock also tends to be more resistant to wrinkling but less tolerant of tight bend or draw radii.
Tooling for deep drawing tends to cost more upfront than simple bending dies because the punch, die, and blank holder all have to be precisely matched to the material and geometry. For high volume parts, though, the per-part cost is often lower than fabricating an equivalent shape from multiple welded pieces.
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