Top Tips To Facilitate Rockwell Hardness Tests

hardness test

Hardness is defined as the measure of resistance that a material has when force is applied to it. Others may refer to hardness as the ability of a substance to resist scratching, cutting or abrasions. There is a direct relationship between the level of hardness of an object and the level of its resistance. The greater the hardness, the greater the resistance. Hardness is largely determined by a substance’s microstructure. Hardness matters because it gives us an indication of how the material will stand up against pressure. This has implications on how the material can be used and what kind of pressure it can withstand. For this reason, measuring hardness is a routine procedure in most quality control processes. Here are some of the ways of facilitating Rockwell hardness tests.

Check Indenter

Before carrying out a Rockwell hardness test, it is critical to ensure that there is no chipped or cracked diamonds on the indenter. This is because any of such anomalies are likely to lead to errors in the readings. Experts recommend checking the indenter every week with a magnifying device (such as a Jeweler’s eye loop). However, it might be hard to tell if the indenter is damaged. For this reason, if you notice consistent erroneous readings, this might be another clue that there is a problem with the indenter.

Verify Hardness Readings

Before performing a test, experts recommend that you test the hardness of a test block. This is a block with a hardness that is already known and thus the idea is to check if the reading from the tool is consistent with the known hardness. It is usually standard to do at least three tests in order to establish a consistent reading. It is also standard to discard the first reading after an indenter or an anvil change.

Keep the Rockwell Hardness Tester Clean

Debris, dirt and other contaminants can affect readings. It is important to remove and clean the indenter and anvil before you start testing. It is also critical to do this at every break between the shifts so that all parts of the tester stay clean throughout the day.

 Smoothen Surfaces

When testing objects that are rough or that have textured surfaces, it is important to be aware that these kinds of surfaces can affect the readings obtained from the tester. To help overcome these kinds of problems, ensure that you lightly sand the surface to reduce the roughness.

Watch out For Movement

If you get any movement of the part while doing a test, you should discard the reading and perform another test. You should also avoid including these readings in your final average. This is because the movement of the part can affect the accuracy of the test.

Watch out for the Edge

When you take readings very close to the edge, it might cause problems with the reading and might even damage the indenter. Ensure that all readings are made at least 2.5 times the diameter of the indenter from the edge. The key to note is that if the metal buckles outward, then you have positioned the indenter too close to the edge.

Top Tips To Choose A Film Thickness Gage

thickness gage performance

A film thickness gage is one of the most essential instruments used in the coatings industry today. Errors in film thickness estimates lead to a significant waste of money, material and time. If a coating application makes a dry film excessively thick, this leads to failures such as flaking, cracking or excessive drying time. In the event that a film is excessively thin, its protective capabilities and hiding power become inadequate and time is lost by having to recoat the entire surface. 

For these reasons, it is important you know how to properly select a film thickness gage. Below are some key factors you can consider when choosing a film thickness gage:

Film Thickness Gage Performance

When choosing this type of thickness gage, always keep in mind its level of performance. A good question to ask yourself is how precise or accurate you need it to be. A high performance gage is needed if you are applying less than 1.0 mil of dry paint film. If you want to further improve your accuracy, choose one which has single or a two point calibration feature. Remember, the gage can be calibrated in line with certified film thickness standards. 

Substrate 

Always consider the substrate the coating is being applied to when choosing a thickness gage. Is the substrate metal or non-metal? If it is metallic, the metal is either ferrous, such as steel, or non-ferrous, such as aluminum. It is worth noting that ferrous metals have magnetic properties, unlike their counterparts, the non-ferrous metals. 

ISO Compliance 

You might be required to document your measurements for ISO compliance. In this case, a film thickness gage with computer interface capabilities and memory is your best choice.

Measurement Area

Another important factor to consider when choosing a film thickness gage is the measurement area location. You will need an exterior probe sensor when measuring inside corners, pipes, and very small surfaces. Unfortunately, when external probe sensors come into play, the choice of film thickness gage models becomes quite limited. 

Certified Thickness Standards

It is recommended you get a certified thickness standard to check if the gage is performing as required. 

Bottom Line

Before choosing a film thickness gage, there are some important factors you should have in mind. For effective coating to take place, you need a well measured film thickness gage. 

Willrich Precision Instrument offers a wide range of film thickness gages that can meet all your gaging and inspection needs. We are an ISO certified company and have been the premier provider of precision measurement systems for over four decades. Our staff is knowledgeable and ready to help you with any questions you may have regarding your metrology needs. Feel free to contact us to discover more about the products and services we offer.

Understanding Height Gage Measurement Procedures

Height Gage Measurement Procedures

Height gages are useful instruments when one needs to measure the height of an object. They come in many different forms and modern height gages can also be used to measure internal diameters among other things. Electronic height gages can be very precise and often claim a consistency of ±0.0001in. Height gage measurement typically involves a moving arm with a pointed end that is usually in contact with the object that is being measured. In the old gages, readings were taken off a vertical and calibrated shaft. Modern height gages have a digital display where readings are displayed.

In recent
years, digital height gages have become the preferred choice in many machining
shops. They are made with hardened stainless steel and a heavy base. This makes
the instrument stable and ensures that any reading made are accurate. Digital
height gages also come with data ports that allow the machine operator to
transfer data from the gage to a computer. From there, the data can be printed
or stored for later use.

Preparing
the Gage for Use

It is
wise to start the process by cleaning the bench from which you are working. Any
objects or particles on the surface can affect the stability of the height gage
and in turn affect the accuracy of the readings. To get the best results from
your height gage, always ensure that the base of the gage is resting flat on
the surface of the workbench.

Once
that is done, dry the sticker on the digital height gage and fix the measuring
arm on the gage after cleaning it. At this point, ensure that all the LCD displays
and controls of the height gage are working flawlessly. You should also clean
the surface of the item you are measuring with a cloth to ensure that there are
no impurities on the surface of the object.

Using
the Gage

When
it comes to taking measurements, move the measuring jaw so that it gently
touches the platform surface. If the machine is set correctly, the value on the
display should be zero. If it is not, turn the machine on and off until it is
zero. When this is done, keep the rod against the surface and move the
measuring jaw to the closest reading. When this is done, take the reading on
the LCD screen.

Things
to Note

If you
have an object that is above the range of the height gage, raise the base of
the gage and place an even block underneath it. Zero-point becomes the platform
surface and the starting point is the top of the block. In such a case, ensure
that you have preset the height of the block. Remember to clean the jaws and the
unit after measurement before storage. You should also avoid applying electric
current to any part of the unit as this is likely to damage the sensitive
electronics in the unit.

If you
are looking for high-quality height gages for your machining processes, Willrich Precision
Instruments
has exactly what you need. We believe in not
just supplying high-quality precision instruments but in building strong partnerships
with our clients. This way, we are always there when you need us for
calibration services and any other kinds of support.

What Is The Proper Way To Read Height Gages?

Read height gages

Height gages allow a machine operator to measure the depth of an object with pin-point
accuracy. These gages differ immensely from model to model but most have the
same basic structure. They consist of an arm that is usually in contact with
the object being measured and a measuring unit that moves up and down the
scale. Height gages typically measure vertical spaces but can also measure
other dimensions such as internal and external diameters. Ever wondered about
the proper way to read height gages? Read on to find out more:

Vernier Height Gages

The
first step when using this kind of height gage is to lock the arm into position
after placing it at the top of the object being measured. When this is done,
you need to then find the ‘zero” on the vernier scale that goes along with the
moving part on the scale. Look at the number on the upright shaft that falls
across the zero marking. Take note of this number as it is the first portion of
your measurement. When this is done, look at the numbered line on the vertical
scale that best aligns with a line on the vertical shaft. This number becomes
your final portion of measurement. The final step is to combine the zero
measurements with the best-aligned measurement to get the final height
measurement of the object you are measuring.

Dial Height Gages

Start
with positioning that arm in place at the top of the object that you want to
measure. When this is done, take note of the last number located beneath the
measuring equipment on the shaft. These numbers are likely to be in increments
of 0.1 inches. Take note of the number that the needle is indicating on the
dial face. The final step is to combine the measurement that you took on the
vertical shaft with the measurement that you noted from the dial face. The
combined number that you get represents that height of the object that you are
measuring.

Digital Height Gages

When
taking measurements using this type of height gage, place the arm in position
at the top of the object that you wish to measure. When this is done, find the
digital display on the height gage and take note of the number that is shown on
the display. This number is the height of the object that you are measuring.
With digital height gages, you do not have to take the ‘zero’ setting as this is automatically
set by the gage when you switch it on. For this reason, digital height gages
are very popular as they can give readings much faster than the other two. This
ability is critical in a manufacturing process where the quality control
officers have to randomly test samples from the production line without slowing
down the production process.

Looking
for high-quality height gages? Willrich Precision Instruments has been
providing clients with the best precision instruments for over four decades. We
are a one-stop-shop for all your precision instrument needs.

How to Make the Most Out of Your Height Gages

height gages

Height gages are used to measure a lot more than just heights. These useful measuring tools trace their origins back to the 16th century when Pierre Vernier developed the vernier scale. This scale allowed mathematicians and engineers to measure accurately. So good was his system that the scale became the standard of quality measurements for the next four centuries. From this, the vernier height gage and the gear tooth vernier height gage were developed and became widely used throughout various industries.

The height gage as since come a long way and a lot of other useful functionalities have been added to it. Its basic design has not changed much though. It looks like a hand-held caliper that rests on a heavy base that keeps the tool aligned to the surface. In the original machines, the scale had a movable jaw that was used to mark a part to indicate a measurement. Here is how to get the most out of your height gage.

Setting it Up

Before you can use your height gage, you will need to set two references. The first of those is the zero-reference which the tool is able to set automatically. It does so by moving to touch the surface to set a reference point. Machining experts recommend that you do this process twice so as to ensure that no dirt or other anomalies interfere with the reference.  The other point of reference is correcting for probe ball diameter. This reference does not matter very much if the gage is only being used to measure heights. 

If, however, the gage will be used to measure grooves or diameters, then it is important to take the probe ball diameter into account. For most modern height gages, the probe ball diameter is measured automatically and its dimensions automatically factored into all readings. The machine takes a fixture that comes with the gage which sets up a plane. This plane is measured from the two opposing directions and the difference between the two measurements is taken as the ball diameter.

How to Measure

Modern digital height gages make it easy to take any measurement. All the operator needs to do is to slide the measuring carriage across the part that is being measured and press a button. The gage will move the carriage from the top to the surface and print out the height reading on the display. Modern height gages allow the operator to manipulate and share data. They come with data ports and other useful connectivity options that allow for the transfer of data to computers and other platforms for analysis and storage.

Things to Look Out For

One of the most common sources of bad readings from height gages is when an operator takes higher than recommended height measurements without changing the base. When this happens, the gage wobbles (although this may not be discernable) and this influences the measurement.

Maintain Proper Air Supply And Tooling Maintenance For The Best Air Gaging Results

air gaging

Air
gaging is similar to mechanical gaging in several ways, e.g., they are best
used in dry, clean, and tight conditions. Although air gages are more reliable
and durable than mechanical gages, it does not mean they don’t need scheduled
maintenance. This means that air supply vigilance and proper tooling
maintenance is required to enhance air
gaging
accuracy. Below are some tips on air supply
and tooling maintenance to help you achieve the best possible results:

Check
for Balance Errors

Balance
error tests are often performed by first rotating the air
tooling
to allow the jets to be mounted vertically.
The master is then placed on the plug, and if done correctly, it will rest on
the top jets and note the reading. Remember to lift the master so that it restricts
the lower jet as well. Oftentimes, the two-jet air plugs will automatically
balance themselves (one jet will be closer to the workpiece than the other). If
you notice one of the orifices or jets is worn or damaged, it means that the
test has demonstrated that the gage cannot maintain that balance.

Because
plug gages contact the workpiece across a broad surface area, they tend to be
pretty durable. This, however, does not mean one can ignore the possibility of
poor balance or lack of centralization. It is important to perform these tests
as part of one’s annual gage calibration plan.

Be
Mindful of the Air Supply

The
process of compressing air is known to produce moisture. As compressors also
need to stay constantly lubricated, oil mist is often found in the line as well.
That’s why shop air is significantly difficult to keep dry and clean. When
water mixes with oil, these elements act as an abrasive and can cause premature
part wear over time. With that in mind, avoid letting air continuously run
unless it becomes necessary to do so. This is a good way to prevent mist from
entering the gage and damaging the jets.

To
keep air supply quality in check, it is recommended that one employs proper air-line
design that intercepts moisture before it enters the meter. Consider pitching
down the air main lines from the source by installing a proper trap on the end;
placing filter in operating gages; bleeding air lines before they are connected
to the gages; and taking air from the top of the mains.

Inspect
for Signs of Wear

Although
air gaging does not involve metal-to-metal contact between the workpiece and
gage component, air gage tooling typically makes contact with the workpiece and
may show signs of wear after repeated use. To inspect for wear, below are some
simple steps to follow:

  • Secure the gage with the jets in horizontal
    position.
  • Place a master on the plug, release it, and
    take the reading.
  • Steadily raise the master until it contacts
    the plug’s lower surface.
  • If the readout moves from one chord (through
    the maximum diameter) to another, it means that the plug is worn.
  • If the reading exceeds the part tolerance by
    10 percent or more, it means that there is excessive wear.

Top Tips For Handling Digital Height Gages

digital height gages

Digital height gages are used to perform a
variety of measuring tasks quickly and reliably. Digital height gages are made
up of a base plate with a measuring station and a control display. The
measuring station is designed to measure one-dimensional coordinates
vertically. For this reason, digital height gages are great for measuring
distances between two points on an object or for measuring diameters. Over the
years, operators have discovered other ways of using digital height gages. For
example, if the object being measured is tilted to an angle of 90 degrees, then
measurements can be taken at this angle as well. Here are some tips on how best
to use these useful measuring tools.

Keep
the Gage and Work Surface Clean

Before using a digital height gage,
ensure that the work surface, the contact probe, and the space around the
equipment are clean. This is because dirt and particles on the surface where
the gage rests or on the contact probe can affect the measurements taken by the
gage. It is also important to ensure you zero the gage before you use it. This
is done by switching the gage on and letting it set its reference location.
After a minute or two, repeat the process again and compare the first result
and the second.

Mind
the Temperature

Sometimes, operators using digital height
gages convey their body heat on to the instruments. This causes various
elements of the tool, such as the base plate, test piece, or the stylus to heat
up. This, in turn, produces inaccurate readings due to heat expansion. Operators
should be careful about what they touch and how long they remain in contact
with the elements of the gage. It is also recommended that operators use gloves
when touching the test piece.

One should also avoid placing the digital
gage anywhere near a draft or direct sunlight to avoid cooling or heating up
the gage elements. It is also important to avoid testing parts that have been
transported in a cold or hot facility. Experts recommend letting them ‘rest’ in
ambient temperature for a while before using the digital height gage to measure
them.

Keep
the Gage Working Properly

It pays to constantly inspect the gage for deflections
on the contact points where they touch the part. This happens when the contact
point is long and this can affect the accuracy of the measurements that are
taken. When deflection is noticed, one has the option of building a
reinforcement bridge on the contact so as to minimize the effect of the
deflection

Other Tips

Machine operators can improve the measurements they take by avoiding radiators in the proximity of the digital height gage. It is also important to use the air bearings to position the height measuring instrument. If you are using a digital height gage with a motor drive, one can improve the accuracy of the measurements by using a constant gaging force when the test piece is being measured or inspected.

How to Measure Counterbores And Blind Holes with Air Plug Gages

Air plug gages

Air plug gages are used to perform a
variety of tasks around the workshop. Some of these tasks include measuring
blind holes (also known as counterbores). An air plug gage is made up of a
cylindrical body that provides the guide for air jet positioning in the bore.
The nozzles that release the air are contained inside this body and this
essentially makes the air plug gage a non-contact measuring tool. The internal
nozzles also help to protect the air jets from being damaged. Air plug gages
also clean out the surface of the object being measured through the air jets,
leading to greater accuracy when measuring. So, how does one use these air plug
gages to measure blind holes?

Measuring
Blind Holes

When measuring blind holes with an air
plug gage
, one must ensure that the hole is free of any contaminants.
Debris and pieces of wood or metal in the blind hole can lead to false readings
from the air plug gage. One must also ensure that they are using the right size
of the tool and that the gage is properly maintained. Typically, the air jets
clear most of the debris away but it is useful to regularly inspect the nozzles
to ensure that they are clean.

When using air plug gages, the gage will
automatically center itself in the hole being measured and reduce (if not
completely eliminate) the probability of angular error. This makes the gage easier
to use for operators who have limited experience in using air gages.

Take
Note of Tolerances

Apart from selecting the correct air plug
gage for the blind hole you want to measure, there are a number of things to be
on the look-out for. The first is to be aware of the tolerance that you are
measuring for.

Consider Different Surface Finishes

The other thing is to be aware of the
surface finish of the blind hole that you are measuring. Various surface
finishes can give different readings. This is because the air plug gages
measure the average of peaks and valleys that the air jets encounter.

Avoid Rushing to Take Measurements

The other thing to note when using air plug
gages to measure blind holes is to be patient with the readings. This is
because all air gages measure the backpressure created by the air inflows that
‘bounce off’ the part. If the backpressure takes a while to fill up, then
taking a reading immediately will probably give you bad results. This is
unlikely to be a problem when measuring blind holes in a simple workshop but if
this is happening as part of an automated manufacturing process, then bad
timing can result in wrong results.

Air plug gages are effective in measuring
blind holes provided that they are used properly. Willrich Precision Instrument stocks a
variety of high-quality air plug gages for all your precision measurement needs.

5 Golden Rules of Air Gaging

Air Gaging

Air gaging is a useful and effective method to measure hard to reach spaces such as small holes. Air gages have the additional advantage of being easy to use and are very flexible. Air gages are non-contact measuring devices and they are useful for measuring objects and surfaces that are extremely sensitive. When you are using air gages, there are some things that you need to keep in mind in order to produce the most accurate results possible.

Understand What You Are Measuring

Although this sounds obvious, it is not always the case that operators are clear on what they are measuring. Air gages can measure a variety of things including diameters, partial diameters, squareness, straightness, and more. Understanding what you want to measure will determine the usefulness of the data you get from the process.

Where Are You Measuring?

Air gages and the air jets that they use can measure a wide variety of spaces. One of the rules of air gaging is that the air jets have to be covered by the surface that it is measuring. When using an air gage, it is critical to understand that the air needs a path in order to accurately measure the dimensions of a hole. When you are measuring a blind hole, it can pose certain challenges.

Consider the Surface being Measured

When using an air gage, the finish (or roughness of the surface) will also have an effect on the reading that you get from the measuring device. If you were to use a contact-type gage to take the same measurement, there is a possibility that the two readings will be completely different.

Backpressure May Delay the Process

For an air gage to work properly, it is essential for the air channels and the air pipe in the machine to fill up due to the back pressure. This back pressure is created when the airflow from the jets are restricted by the part being measured. If the air pipes are long, this process can take a while, and in certain applications such as high-speed automated gaging, it might lead to incomplete results. One way to solve this problem is to bring the converter as close to the surface being measured as possible to reduce the length of the air pipes. The second way is to ensure that the air in the tool does not flow out of the part between measurements. This means that the air hoses take a shorter time to fill up as they would already have a significant amount of air from previous measurements.

Altitude Matters

The height of your location plays a part in the performance of your air gage. This is because air is thinner at higher altitudes and this can affect the performance of the equipment. Since most air gages are custom made for specific tasks, ensure that you ask your supplier to take the altitude of your location into consideration when calibrating the machine. This is also something to keep in mind when moving the equipment from one manufacturing plant to another.

How To Deal With Height Gage Challenges Like A Pro

height gage

Technicians may encounter some challenges when using larger height gages. The cause of those potential problems is not due to the height of the gage but its relationship to the size of the base. If there are errors in how the gage is set up, it can potentially distort a carefully planned height measurement procedure; that said, what can you do to get perfect measurements for every job and overcome said height gage challenges?

Keep and Use a Well-Maintained Surface Plate

A majority of height gages are typically used with surface plates. These surface plates are designed to provide the reference for both the height gage and the part that’s being measured. It is imperative that these plates are well-maintained and clean. When measuring a workpiece that has a height of approximately 10 inches, a strand of hair or a small metal chip is enough to throw off one’s measurements by 0.020 inches.

In addition to minute dirt and debris, the surface of the granite plate also plays a major role in performance of the height gage. The slightest imperfections can be amplified if the surface between the workpiece and height gage is not smooth enough, is uneven, etc. This may cause problems if the measurement gets higher. Here’s a quick scenario:

  • The surface plate of your height gage has a flatness spec of 50 microinches
  • The base has a length of six inches
  • Imperfections on the granite plate’s surface can cause a 50-microinch error to grow over 0.0003 inches

Lengthen and Widen the Base

A height gage is designed to measure a specific height. That’s the point where it performs at its best. If the height gage model you are using is designed to measure 24 inches, you can’t simply extend the post to measure a part that’s three times that height. If the cross area of the measuring post or base design is not modified, the gage can start to flex and/or wobble, affecting the final measurement. Oftentimes, it is hard to spot if these problems are occurring at that moment. For example, a 0.001-inch wobble is invisible to the naked eye.

To prevent the post from flexing or wobbling, some technicians may focus on “strengthening” the column of the height gage. Unfortunately, this is not a viable solution for resolving the problem. If pressure is applied to the measuring contact when it’s nearing the maximum upper position, the gage may tip over. If the same amount of pressure is applied horizontally against the gage’s measuring contact, the gage may start sliding along the table.

The correct way is to focus on decreasing the ratio of the base to the post. One can achieve this by making the base wider and longer. In addition, build in some mass. By doing this, one can expect to see significant improvements in the height gage’s performance.

Looking for a reliable height gage? At Willrich Precision, you can purchase high-performance height gages online at the best prices. Feel free to contact us if you have any inquiries.