A custom alloy-steel gear manufactured with a controlled relationship between the central bore, mounting faces and external teeth.
This large forged spur gear was manufactured by BestPro for a low-speed, high-torque industrial transmission. The customer’s dimensions and gearbox details remain confidential, so this case focuses on the manufacturing points relevant to the component itself.
The gear was produced from a forged alloy-steel blank. Its external teeth, large central bore, upper mounting face and bolt pattern all form part of the same assembly relationship.
The main concern was not an individual dimension, but keeping the teeth centred on the bore.
The bore locates the gear in the assembly, while the machined face controls its axial position. If either reference shifts between operations, the tooth circle can run eccentrically even when the bore and teeth each pass inspection separately.
For this reason, the bore and end face were established as the main references and retained through the following machining stages.
The forged blank was rough turned first, with material left on the bore and functional faces for later finishing. After heat treatment and material stabilisation, the central bore and end faces were finish-machined to establish the final references.
The external teeth were then cut in relation to the same centre. The mounting holes on the upper face were completed and checked relative to the bore rather than treated as an independent hole pattern.
The bright surfaces visible in the photograph are functional mounting and locating areas. They were machined for assembly rather than polished for appearance.
Final inspection focused on:
· Bore diameter and concentricity
· Tooth profile and pitch
· Radial runout of the teeth
· End-face runout
· Mounting-hole position
· Heat-treatment hardness
After inspection, the finished gear was placed on timber supports to keep the machined faces away from the floor before protection and packing.
BestPro supports custom large forged spur gear projects from forged blank sourcing through heat treatment, gear cutting, finish machining and inspection. Customers can provide the drawing, material, quantity and required gear accuracy grade for review.
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