Metrology
Metrology
Evaluating Gaging for the Shop Floor
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EVALUATING GAGING FOR THE SHOP FLOOR

Understanding the New IP Standard

George Schuetz,  Mahr Federal Inc.

 

 

Measuring instruments have been used for the inspection of manufactured parts ever since the first vernier caliper was introduced.  It didn’t take much to take care of these old tools out on the shop floor: a clean cloth, a little elbow grease and a good storage box was all that was needed to make those gages last a lifetime.  In fact, they often became prized possessions, as those old craftsman handed tools down from generation to generation.

In the past thirty years or so, electronic gages have become increasingly common on the shop floor because of their ease of use, speed, and ability to do complex measurements.  However, when it came to caring for these new gages, one thing was clear: you didn’t want to get that digital caliper, micrometer, indicator, amplifier or computer anywhere near water or coolant, or there was sure to be trouble.  Either the gage wouldn’t work, or even worse, it would produce incorrect readings.

 This didn’t make sense, of course, that the tools needed in an environment where there was coolant, grease, dirt and chips flying around did not like those conditions.  Recently, there have been improvements in a lot of the electronic gaging that finally gives these tools the characteristics needed to survive out on the shop floor.  Improvements in scale technology, microcircuits and sealing have made gages capable of literally making measurements under water.

Now that these types of gages are finally available, a new standard has been set up to help identify what type of tool is best for the environment in which it will be used.  This rating is called Ingress Protection – IP for short.  Associated with the IP is a two-digit rating number that tells what type of conditions that gage can survive in.  The first digit describes the protection for solid foreign objects, while the second digit indicates protection against harmful ingress of water.  A potential third digit, which is the defined impact protection, has not yet made its way into the measuring instrument table.

For example, a gage might have a rating of IP-65.  As you can see from the accompanying table, this gage is totally protected against dust and protected against low pressure jets of water from all directions, with limited ingress permitted.  Today there are calipers and micrometers with ratings as high as IP-67.  These can be subjected to the type of dust and dirt found in the shop and is both water and coolant proof.

So, electronic tools that can finally be used on the shop floor – what a good idea!  But one cautionary note - - just because these new gages can handle the environment doesn’t mean their measurements are impervious to environmental conditions.  They are still precision gages and all the basic rules for precision gaging still apply.  We’ll review the classic SWIPE paradigm in one of the next issues.

First number (Protection against solid objects)

 

 

Definition

 

 

Second number (Protection against liquids)

 

 

Definition

 

 

0

 

 

No protection

 

 

0

 

 

No protection

 

 

1

 

 

Protected against solid objects over 50 mm (e.g., accidental touch by hands)

 

 

1

 

 

Protected against vertically falling drops of water

 

 

2

 

 

Protected against solid objects over 12 mm (e.g., fingers)

 

 

2

 

 

Protected against direct sprays up to 15o from the vertical

 

 

3

 

 

Protected against solid objects over 2.5 mm (e.g., tools and wires)

 

 

3

 

 

Protected against direct sprays up to 60o from the vertical

 

 

4

 

 

Protected against solid objects over 1 mm (e.g., tools, wires and small wires)

 

 

4

 

 

Protected against sprays from all directions - limited ingress permitted

 

 

5

 

 

Protected against dust - limited ingress (no harmful deposit)

 

 

5

 

 

Protected against low pressure jets of water from all directions - limited ingress permitted

 

 

6

 

 

Totally protected against dust

 

 

6

 

 

Protected against strong jets of water, e.g., for use on ship decks - limited ingress permitted

 

 

 

 

 

 

 

 

7

 

 

Protected against the effects of temporary immersion between 15 cm and 1 m. Duration of test 30 minutes

 

 

 

 

 

 

 

 

8

 

 

Protected against long periods of immersion under pressure