Drill Bush FAQ

Clevis Pin Frequently Asked Questions

Question 1

How do I choose the right drill bush for my application?

Choosing the right drill bush for an application involves considering several factors to ensure it meets the requirements of the specific machining operation. These vary from the types of material involved, the accuracy required and the frequency of use.


Material compatibility

Consider the material being drilled and the cutting tool being used. Different materials have different hardness and characteristics, which can affect the choice of drill bush material. For example, repeatable use of carbide drill bits may require an equally hard or abrasive resistant material, such as tungsten carbide or Nitralloy. The base material of the fixture can also influence the bush type. There are serrated versions for plastic, wood and aluminium with differing features such as fully serrated and grooved ODs, or part serrated OD’s. The help to lock the bushes in place, rather than press fit them. Press fit versions also appropriate for plastics, wood and aluminium, but also suitable for steels, are more accurate as they are pressed into holes with a tolerance, or located into bushes with a ground ID. 

Size and fit

Determine the required outer diameter of the drill bush based on the hole size in the jig or workpiece. The drill bush should have a press fit in the hole to provide stability and accurate guidance. Additionally, consider the inner diameter of the drill bush to match the drill bit or cutting tool size.

Tolerance requirements

Evaluate the desired level of precision for the application. Consider the required tolerance for the hole placement and alignment. Choose a drill bush with the appropriate bore tolerance to ensure the desired level of accuracy is achieved. Drill bushes are manufactured as standard to drill bit limits. For instance, as 7mm drill bit will fit a 7mm bore bush. Reamer tolerances are also manufactured.

Durability and wear resistance

Assess the anticipated usage and the forces involved in the drilling operation. Select a drill bush made of a material that can withstand the demands of the application without excessive wear or deformation. Hardened steel or other durable materials are commonly used for drill bushes as standard. Through hardened materials offer longer life at an economical price point, whilst Nitralloy from manufacturers such a Boneham, offer comparable wear resistant properties to carbide at a lower price and delivery point. Renewable bushes are an ideal solution for high production environments or multiple pilot, drill and ream operations. In high production environments, the renewable bushing can be replaced once worn out.

Pros of using drill bushes

Improved accuracy:

Drill bushes provide precise guidance for the drill bit or cutting tool, resulting in accurate hole placement and alignment. This is especially beneficial for applications that require tight tolerances and repetitive exact hole drilling. This is vital in manufacturing environments, both factory and MRO, that require repeatable and accurate hole making. 

Increased efficiency:

By utilising drill bushes, the setup time for aligning and positioning the workpiece is reduced. This improves the efficiency of the machining process, as the drill bit can be consistently guided without the need for constant measurement and alignment. Multiple hole sizes with the same OD can be achieved with renewable bushes.

Heightened repeatability:

Drill bushes enable consistent and repeatable results, ensuring that the same hole positions and alignments can be achieved across multiple workpieces or batches.

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