Avantages

Define bore depth and axis

Show the internal feature’s location, depth, datum axis, and mating relationship.

Specify required form

Call out size, roundness, cylindricity, or finish only where the design needs those controls.

Show measurement access

Include adjoining shoulders and geometry that affect inspection of the bore.

Align process sequence

State relevant preceding operations and the condition in which the bore should be measured.

Preparing an internal grinding drawing

Identify the bore and its purpose

Internal grinding is used to finish a cylindrical internal surface when the design calls for a defined size, form, or finish. Show the bore location, depth, axis, and its relationship to the component datums and mating part. Include the material, quantity, part number, and drawing revision.

Call out size, form, and surface requirements

Specify the final bore dimension and any required roundness, cylindricity, position, or surface finish controls that apply. Use the drawing standard and units, and distinguish functional features from reference dimensions.

Show access and nearby features

Include bore depth, entry conditions, shoulders, reliefs, cross holes, and adjoining geometry that can affect tool access or measurement. If the bore follows heat treatment or another operation, state the process sequence and inspection condition.

Plan how the bore will be checked

Identify the required measurement method or report, especially where depth or geometry limits access. Confirm that the acceptance criteria can be evaluated from the drawing and purchase scope before the order is released.

Compare the requested process scope

Send the same revision, material, quantity, bore requirements, finish, sequence, and inspection scope to each supplier. Ask what is included and list any assumptions or exclusions.

Foire aux questions

What information should an internal grinding RFQ include?

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Provide the drawing, material, quantity, bore size and depth, datum axis, form and finish requirements, adjoining features, process sequence, and inspection scope.

Do I need to specify roundness for every bore?

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Only where the design requires it. The drawing should define the applicable geometric control, datum, and acceptance criteria.

Why include bore depth and nearby shoulders?

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Depth and adjoining geometry can affect process access and how the finished feature can be measured.

How should the bore be measured?

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State the required method or report in the purchase scope and confirm that it addresses the specified size, form, and measurement condition.

How much does internal grinding typically cost, and what factors influence the pricing or process timeline?

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The cost of internal grinding varies widely based on part complexity, material, tolerances, and production volume. For a single prototype or small batch, you might expect to pay $50 to $200 per part, while high-volume runs can reduce per-unit costs to $5 to $30. Key pricing factors include: the difficulty of accessing the bore (e.g., deep, small-diameter, or blind holes require specialized tooling); the required surface finish and tolerance (tighter specs increase cycle time and scrap risk); the material hardness (hardened steels and ceramics wear wheels faster); and setup time, which can be 1–4 hours for complex geometries. The process timeline also depends on wheel dressing frequency and the number of passes needed. To get an accurate quote, provide a detailed print with material specs, required tolerances, and surface finish. Many shops offer volume discounts, and using CNC-controlled machines can lower costs by reducing manual intervention. Always request a process review to identify potential cost-saving adjustments.

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