How Are Fixture and Jig Costs Amortized? First Agree on the Allocation Basis, Then Discuss Unit Price

Fixture and jig costs appear on CNC quotations because they are a one-time investment that cannot be directly included in the machining cost of a single part. When a part has a special geometry, small batch size, high precision requirements, or when multiple machines share the same set of fixtures, the machining shop must design and manufacture additional fixtures, and the cost must be allocated by agreement between the buyer and seller. At Yuan Shun Li, common fixture types in CNC turning, milling, and Swiss-type lathe machining include lathe chucks, milling machine vises, vacuum suction fixtures, and custom locating blocks. If buyers do not proactively mention fixture allocation during the quotation stage, the machining shop often embeds the fixture fee into the unit price, leading to discrepancies between prototype quotes and mass production quotes. It is recommended that buyers provide suppliers with two pieces of information from the start: whether custom fixtures are needed and the estimated total production volume, in order to obtain comparable quotation bases.

Fixture costs typically include five major items: design fees, material fees, machining fees, assembly fees, and testing and verification fees. The sum of these five items constitutes the total fixture investment. Design fees cover 2D and 3D drawing, clamping point planning, and tolerance analysis. Material fees vary depending on the fixture body material; aluminum alloy fixtures are lower in cost, while tool steel fixtures such as SKD11 or SKD61 are higher in cost but have a longer lifespan. Machining fees are directly related to the CNC machining hours of the fixture itself. Assembly fees include locating components, clamping plates, screws, and other accessories. Testing and verification fees confirm whether the dimensions and roundness after clamping meet the tolerances. At Yuan Shun Li, when processing materials such as aluminum alloy, stainless steel, carbon steel, and brass/copper, we recommend different fixture materials based on part characteristics. When buyers receive a quotation, they should check whether these five items are listed separately. If they are all combined into a single "fixture fee," it will be difficult to renegotiate prices for subsequent additional orders.

The handling of fixture costs during the prototype stage directly affects the starting unit price for subsequent mass production, so it must be clarified at the time of prototype quotation. There are three common approaches: first, the buyer bears the full prototype fixture cost, and production fixtures are remade and re-amortized for mass production; second, the buyer bears the full prototype fixture cost, but the same fixtures are used for mass production, and the original fixture cost is re-amortized based on actual production volume; third, prototype and production share the same fixtures, with the fixture cost quoted as a one-time fee and a total amortization quantity agreed upon. At Yuan Shun Li, when handling OEM parts supply and prototype development projects, we recommend different options based on part complexity. If the buyer only does prototyping without mass production, the fixture cost should be fully borne by the buyer. If mass production will follow prototype confirmation, the conditions for fixture reuse and the re-amortization mechanism should be agreed upon to avoid paying twice—once at the prototype stage and again at the production stage.

The way to avoid hidden or inflated fixture costs is to require the supplier to provide fixture design drawings, material certificates, and machining time records as supporting evidence for the quotation. Buyers can ask the supplier to explain why a specific material was chosen for the fixture structure, why the clamping points are configured in a certain way, and why the machining time falls within a certain range—these questions effectively test the reasonableness of the quotation. Under the ISO 9001:2015 quality system, Yuan Shun Li maintains records of fixture design and manufacturing processes, and buyers can request relevant documents. Another common warning sign of inflated costs is when "fixture costs account for too high a proportion of the total quotation." Generally, fixture costs may account for 20% to 40% of total costs in small-batch prototype runs, but they should decrease as the amortization quantity increases during mass production. If fixture costs remain disproportionately high during the production stage, it is worth asking further questions.