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Progress and development

Seal design, prototyping, and customized solutions

Producing high-performance seals normally begins in the design phase with prototyping and testing. While injection molding is ideal for production en masse, it’s cost-intensive and not best-suited to seal prototypes. And with new technologies such as 3D printing not ready in terms of material properties, machining leads the race in seal production.

During product development, prototypes help assess the functionality and reliability of a product before investing considerable resources into full-scale production. But what options are available for manufacturers to provide customers with cost-efficient, wear-resistant prototypes and products in short lead times?

Injection molding: High repeatability, low efficiency

During the process of injection molding, a polymeric material is injected into a mold. As seals are usually made of softer materials, injection molding might sound like an ideal method for producing flexible seal prototypes. However, as injection molding requires a mold to be produced, initial costs can be high. While this might not be a problem for where mass numbers of the same item are needed, it is not as cost-efficient in cases where small batch numbers are required. Time is also an issue, especially as the method often demands multiple molds to be created before a design is perfected and finalized. For this reason, it is not well-suited to producing one-offs such as prototypes.

Rapid prototyping—3D printing an option?

3D printing, or additive manufacturing, has transformed product design, and offers a much faster option for creating prototypes. 3D printers create an item by building layers of a material on top of each other. For this reason, intricate and accurate designs are possible—while also minimizing wastage. As opposed to injection molding, initial costs are not as high with 3D printing. The technology opens up possibilities for relatively affordable one-off prototypes or bespoke parts in small numbers. However, some argue that accuracy in repeatability could be an issue. 3D-printed prototypes may demonstrate how a part will fit, but cannot necessarily withstand extreme temperatures or pressure during field testing. In its current state, 3D printing is a long way from producing prototypes with the functional and mechanical properties that will allow them to be used as operational seals.

A revolution in machining

Machining is a common method for creating parts and prototypes from metals and harder materials. However, many seals are made of softer materials which were previously difficult to machine. A softer material requires an increased level of pressure control and accuracy from a cutting tool as not to disrupt design precision. Creating a flexible seal from rubber or flexible thermoplastic elastomers therefore requires coordination between the machining process and extraction as well as tools that are optimized for elastomers. An important factor is also the material for the semi-finished product: this needs to be stiff enough to be machined yet flexible enough to function well as a seal when finished.

Machining tools such as SKF SEAL JET can produce custom-made prototypes in very short production times. Computer numeric control (CNC) production systems ensure that an accurate amount of steady pressure is applied to softer materials to shape the seal prototype and a suction unit clears waste material from the work area. Depending on the availability of the right semi-finished product, a prototype can be produced in just a few minutes.


SKF operates more than 90 machining centers worldwide, serving customers in multiple industries. The innovative machining system SKF SEAL JET minimizes manufacturing and dispatch time. It supports companies with a production method that is customizable, affordable, and capable of producing seals within minutes. In addition, materials specially developed for the machining process enable optimized quality in the seal’s physical properties. Material properties and sealing behavior are also simulated using finite element analysis (FEA) software. SKF performs an extensive range of tests on both its materials and seals to maximize standards of quality and reliability.

Saving costs, shortening production time

Advanced machining designed to work with flexible but wear-resistant materials provides a solution to producing durable, customized seal prototypes. It is also precise and cost-efficient. With shorter lead times, increased quality and accuracy, and lowered cost outlay, no batch size is too small and customers receive the ideal product or prototype for their equipment. In this way, testing and implementing the right seal is much more efficient for all parties.