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Meet the Solution Designed for Thread Inspection

For automotive, aerospace, and many other industries, inspection threads is of vital importance due to stringent requirements and intense operating conditions and the resulting consequences of threading failure, specifically within the oil & gas industry. The Gulf oil spill of 2010 is a case in point, and we still see ramifications today all the way down to pipe thread inspection due to this specific threaded pipe failure.


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As one of the most important industrial fasteners, screw threads are found practically everywhere and smooth operating threads that connect parts under intense stress and strain are a vital part of the equation when it comes to industrial pieces of equipment. And as certain applications become increasingly more critical failure can often lead to catastrophe. So in turn manufacturers must ensure leads, pitches, diameters, tapers, and angles are uniform, free of occlusions or defects and in keeping with tight tolerances.

Manufacturers, in order to prove that quality requirements are met, need to ensure quality is fed right through the production process and is just as important upstream with the cutting tool itself. That is where ZOLLER UK step in, but first let’s examine the pros and cons of the most common methods of thread measurement.

Simple Thread Gauges

A convenient way of checking critical part threads is by using a simple thread gauge. Inspecting the fine thread profile and pitch, thread gauges certainly have their benefits. Simple thread gauge require minimal training and with correct usage of both GO and NO-GO gauges the component can be judged as good or bad.

Although this common method is convenient it also has its disadvantages. Using the simple thread gauge method will only reveal if components are good or bad and not the relationship to the tolerance. Gauges are also extremely time consuming during machine setup and when performing process control, as well as difficult and expensive to calibrate.

Manufacturing tolerances and wear on the gauge generally give less tolerance on the actual components to be inspected and individual gauges are limited to the specific thread and tolerance of that particular gauge.

Micrometer Measuring Wires

Another common thread measurement method is a hand-held 3-wire measuring system, which works by placing three wires of known thickness into the screw heads, and a micrometer measures the protruding wires. This displacement method is often more consistent and accurate than using a simple thread gauge, with the added benefit of having the ability to calibrate gauges or use it directly in measuring production parts.

However the 3-wire micrometer method still has its disadvantages due to being suitable only for measuring external threads and thread pitch diameter. This approach also requires extra time needed to carry out calculations in order to find the correct measurement result. Additionally measuring wires are purchased to fit the relevant micrometer spindle diameter.

Special Micrometer Thread Inserts

Thread inserts for special micrometer measurement work by using a pin which holds the thread in place and by calculating the distance between the pin tips to where they sit in the micrometer. This method is a common choice of thread measurement due to its effectiveness. Advantages include accurate results given that the correct flank angle is assumed, the ability to measure all threads with the same flank angle, as well as its suitability for machine setup and process control. However this method is only suitable for external threads and measurement of thread pitch diameter. Thread inserts for special micrometer require set-up when used with a micrometer larger than 0-25mm, costing valuable time.

There are many other methods of thread measurement including thread geometry measuring fixtures, digital calliper and thread inserts. As well as a combination of devices such as a ‘GO’ thread plug or ring gauge alongside measurement of the thread pitch diameter to ensure both profile and pitch are measured correctly as well as generating a correct reading of the part’s positioning within tolerance. However due to manual part handling often mistakes are made and thus valuable time and cost is spent eradicating unnecessary errors.

The Solution?

Meet ZOLLER UK’s high-end universal measuring machine specifically designed for thread inspection. threadCheck offers distortion-free, micron-precise accuracy in the measurement of helical tools, such as taps and hob cutters. With fully automated operation using pilot 3.0 image processing technology, »threadCheck« requires minimal operator interjection, allowing your thread measurement process to become faster, smarter and more productive.

With six CNC-controlled axes and a fully automated optic carrier, threadCheck enables complex measurement of all threaded tool geometries, including threaded taps, cutters, forms and many more variations of cutting tools. Detailed recording allows manufacturers to provide customers with solid evidence of product quality and the photo-realistic modular design of pilot 3.0 software allows threadCheck to meet a host of customer requirements.

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