Fineblanking Manufacturing Company

Fineblanking vs. Double Disk Grinding for Flat Parts

Fineblanking and double disk grinding solve different problems on the same kind of part. Fineblanking is a stamping process that produces a clean, nearly full edge in one stroke. Double disk grinding is a machining process that sets thickness and makes both faces flat and parallel. Fineblanking controls the edge. Grinding controls the faces. Plenty of parts need one, some need both, and buyers often confuse the two when comparing quotes.

At Northern Industrial Manufacturing, we stamp on compound tooling and double disk grind flat parts for automotive drivetrains. This article explains what fineblanking does well, where it stops, and how to tell which process your print actually calls for.

Fineblanking Explained for Flat Parts

Fineblanking is worth understanding on its own before comparing it to grinding.

How Fineblanking Cuts an Edge

Conventional blanking shears the metal, then lets it fracture. That leaves a burnished band near the top and a rough break below it. Fineblanking clamps the material before the punch moves. A ring on the die presses into the sheet around the outline, counterpressure supports the slug from below, and the punch moves slowly. The metal flows rather than fractures, which leaves a smooth, square edge across almost the full thickness.

What Fineblanking Costs

That edge comes at a price. Fineblanking needs a special press with three separate actions and tooling built to tight clearances. Tooling costs more than a compound die and takes longer to build. Press time costs more too, because the punch moves slowly. For parts that truly need the edge, the cost is justified. For parts that do not, it is money spent on a feature the assembly never uses.

What Fineblanking Does Not Control

This is where most of the confusion between fineblanking and grinding starts.

Fineblanking Cannot Fix Coil Thickness

Fineblanking cuts an outline. It does not change the thickness of the steel. That thickness comes from the coil, which arrives with the mill’s tolerance and shifts from coil to coil. A fineblanked part inherits every bit of that variation. If the print calls for a 0.001 inch total thickness tolerance, fineblanking alone will not hold it.

Flatness After Fineblanking

Fineblanking leaves parts flatter than conventional blanking, because the material is clamped during the cut. Flatter is not the same as flat. Stress still goes into the part, and thin parts can still bow. When a print calls out flatness in the thousandths of an inch, the part usually still needs grinding.

Where Double Disk Grinding Beats Fineblanking

Grinding starts where fineblanking ends, working the faces rather than the edge.

Thickness Control That Fineblanking Cannot Match

Where fineblanking stops, double disk grinding takes over, passing parts between two wheels set a controlled distance apart. Every part leaves at that thickness, whatever the coil gave it. Our line holds a 0.001 inch total thickness tolerance, with flatness and parallelism at 0.001 inch and a 10 microinch finish. For a selective fit shim, where thickness steps sit close together, that control is the whole point.

Balanced Forces After Fineblanking or Stamping

Grinding both faces at once keeps the forces balanced. Equal stock comes off each side, so the stress inside the part stays in balance. That helps a part stay flat after it leaves the machine, whether the blank came from a compound die or a fineblanking press.

Material and Thickness Limits in Fineblanking

Fineblanking has its own working range, just as grinding does.

Steels That Suit Fineblanking

Fineblanking works best on steels with good formability, because the metal has to flow rather than fracture. Grades chosen for fineblanking are often annealed to a specific structure before the press. Harder or higher carbon material resists that flow and shortens tool life. Grinding is less sensitive here. We grind carbon steel across the SAE 1008 to SAE 1095 range, including parts that arrive already hardened.

Thickness Ranges for Fineblanking and Grinding

Fineblanking covers a wide thickness range, and thicker material is where it often pays off most, since a clean edge through a thick section is hard to get any other way. Our grinding line runs parts from 0.060 to 0.200 inch thick and up to 6 inches in size. A part can easily sit inside one range and outside the other, which is another reason to check both before committing to a routing.

Volume and Tooling in Fineblanking Programs

Fineblanking cost per part depends as much on volume as on the process itself.

Fineblanking Tooling and Program Life

Fineblanking tooling costs more upfront, so it needs volume and a long program to pay back. A design still in flux is risky, because changes to an expensive die cost real money. Compound tooling is the lighter commitment. It requires a lower upfront investment and shorter lead times, which suits programs that may still change.

Grinding Volumes Alongside Fineblanking

Grinding spreads its cost differently. Setup happens once for a program, then parts feed continuously, so cost per part falls as volume climbs. Grinding programs at our plant begin above 5,000 pieces a year and climb into the hundreds of thousands. That makes grinding practical on programs too small to justify fineblanking tooling.

Parts That Need Fineblanking and Grinding

Some parts genuinely call for fineblanking and grinding together, and it helps to recognize them early.

When an Edge Justifies Fineblanking

Fineblanking earns its cost when the cut edge does real work. Gear teeth, cam profiles, and levers that bear against another part need a full, square edge. Parts with an edge that must be measured or that carries load are candidates. So are parts where a secondary machining step to clean the edge would cost more than the fineblanking tooling.

Adding Grinding After Fineblanking

If a fineblanked part also sets a dimension inside an assembly, it needs its faces ground. In that routing, fineblanking produces the outline and the edge, and grinding brings the part to thickness with flat, parallel faces. The stock allowance has to be planned so the grinder can clean up both faces without cutting into what the edge requires.

When Neither Fineblanking Nor Grinding Is Needed

Not every flat part needs fineblanking or grinding, and an honest supplier will say so.

Simple Parts Rarely Need Fineblanking

A clearance washer or a cover needs neither fineblanking nor ground faces. Conventional stamping on compound tooling produces those parts quickly and cheaply. We use compound tooling exclusively, which cuts the outside and inside features in one stroke and supports concentricity between them.

Checking the Print Against Fineblanking Costs

Before paying for fineblanking, check whether the print is current, since drawings often carry callouts copied from an older part. An edge condition or a flatness requirement may no longer match what the part does. Reviewing each callout against function can move a part off an expensive process entirely, or reveal that it belonged on one all along.

Quality Records After Fineblanking and Grinding

Automotive programs ask for proof, whether the part comes from fineblanking, grinding, or both.

Inspecting an Edge After Fineblanking

A fineblanking edge is usually judged by how much of the thickness came out smooth and how square the wall is. Those checks belong in the control plan, with a stated frequency. If the edge carries load or gets measured in assembly, the print should say what it must hold, not just that it should look clean.

Inspecting Faces After Grinding or Fineblanking

Face requirements are measured differently. Thickness comes from readings at several points, and flatness is checked in the free state on a surface plate. Thickness, flatness, parallelism, hardness, and surface finish all get tested as parts move through our plant. A part that gets both fineblanking and grinding needs both sets of checks, and the control plan should show who does each one.

Choosing Between Fineblanking and Grinding

The decision usually comes down to two questions. Does the cut edge do work in the assembly, or is it simply an outline? Does the part’s thickness or flatness set a dimension that other components depend on? An edge answer points toward fineblanking. A face answer points toward double disk grinding. Both answers point toward a routing that uses each process for what it does best.

US Fineblanking & Grinding Manufacturing Company

Northern Industrial Manufacturing Corp. stamps and double disk grinds flat carbon steel parts in SAE 1008 through SAE 1095, hardened or not, at an IATF 16949 certified plant in the Detroit area. Send us your print. Our team will tell you which callouts drive cost and whether your part needs the faces ground, the edge fineblanked, or both.

If your manufacturing needs calls for precise, dependable fineblanking or grinding, the team at Northern Industrial Manufacturing is ready to support you. Call 586.468.2790 or request a quote today to discuss your project and discover how our double disk grinding services can support your production goals.

Fineblanking & Grinding Services: 586.468.2790