Inspection and Measurement
of Steel Parts
Our finished projects go through a rigorous inspection and measurement process. Precision Grinding, Inc. is proud of the quality of our work and the accuracy of the parts we provide, where we:
- Verify the number of parts, thickness, width and length match the original drawing.
- Measure two hole locations along the Y axis, as far apart as possible, to insure they are located correctly and are parallel with the edge of the plate.
- Measure one of these holes from the X axis to verify it is located correctly.
- Mic the diameter and depth of each drilled, reamed, bored, and/or tapped hole to match customer specifications.
- Inspect each tapped hole to insure the holes are tapped to the correct size, depth and the threads are not galled or torn.
- Spot check different size tapped holes with Go/No-go gauges.
- Have a second inspector verify quantity and quality of all tapped holes to ensure accuracy.
- Check the width, length, and/or depth of each machined area.
- Remove all sharp edges, oil and stack parts neatly.
- Record all inspected dimensions on the inspection report document with inspector’s signature and date of inspection.
Inspection and Measurement Equipment
Precision Grinding , Inc. has all micrometers recalibrated on a periodic basis. The Production Manager is responsible for maintaining the integrity of all Measuring & Inspection Equipment in the machine shop.
Our Measuring Equipment includes, but is not limited to, the following:
- Renishaw Probing Systems – Accuracy specified to 0.0005” – .0.001”
- Outside Mics
- Inside Mics
- Depth Mics
- Vernier Calipers
- Digital Height Gages
- Dial Bore Gages
- Threaded Plug Gages, Metric and Standard
- Small Hole Gages
- Telescoping Gages
- Pin Gage Set
- Precision Jo-Block Set
- Precision 24” Master Square
- Precision Straight Edges
- Master Setting Rings
- Precision Granite Surface Plates
Inspection Probe for Custom Steel Projects
An inspection probe is one of the ways we improve the efficiency our machine tools. Touch probes on CNC machining centers and lathes can be used to set-up parts, measure features in-cycle, and verify finished component dimensions.
Precision Grinding, Inc. proudly uses Renishaw Optical Machine Probes: Accuracy specified to 0.0005″ – 0.001″.
- The Renishaw Optical Machine probe is part of a new generation of optical transmission machine probes that brings the benefits of probing to a wide range of machining centers. It provides users set-up time reductions of up to 90%, reduced scrap, reduced fixture costs, and improved process control.
By using Renishaw probes for set-up, on machine verification, measuring and locating we can:
- Increase productivity and batch size flexibility
- Reduce manual setting errors
- Reduce machine downtime
- Reduce scrap
General Tolerances and Measurements
Unit of Measure
- The standard unit of measurement is inches.
- Metric conversions will be made using 1″ = 25.4mm and/or 1mm = .03937″
- The following tolerances are used unless otherwise specified on the customer’s drawing:
Dimensional and Location Tolerances
|Decimal Precision||Linear Tolerance|
|Fractional (1/x)||=||+/- 1/32|
|Angular||=||+/- 1 degree|
Standard machined finish will be .125 RMS
Reamed holes will be machined to a Press Fit (PF) of .0005″ to .001″ under specified diameter.
- Threaded holes will be chamfered Major +1/32″ approximately 90 degrees from machined side
- Full thread depth will be 1.5x Major diameter
- Minor diameter will be drilled to 65% – 75% thread, depending on material machinability
- Minor diameter will generally be drilled to [(full thread depth) + (tap chamfer length) + .100″] full depth
- Thread fit will be 2B
Counter Bored and Counter Sunk Holes
ANSI standard, as per Machinery Handbook normal fit specifications, will be followed with depth altered to sink application bolt head approximately .015″ below flush
ANSI standard, as per Machinery Handbook normal fit specifications, will be followed.