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The best way to think about a coordinate system is to think of an elevation map with its referencing system that uses numbers and letters to help the map reader select a very precise point on the map. This coordinate system is the backbone of coordinate metrology that in turn is used in Coordinate Measuring Machines or CMMs that ensure that products coming off the manufacturing line meet very precise quality standards. The coordinate system is an invention of Rene Descartes, a French mathematician, and philosopher who created the system in the 16^th century. Here are some of the basic terms that you may hear in coordinate metrology and their meanings.

Coordinate Measuring Machines

Coordinate Measuring Machines or CMMs are precision measuring machines that use the coordinate system to measure the surfaces of a product. CMMs do this by running a probe (which could be mechanical, laser or optical) along a surface and the data collected is then relayed to a data reader. The probe can either be manually controlled by an operator or can be computer controlled. Typically, CMMs will be used alongside other measuring tools such as CT scanners.

Datum

Another common term that you are likely to hear is datum which refers to points on the coordinate system. To use the earlier example of a street map, the datum can be a hotel or a river that is featured on a map. In the world of coordinate metrology, the datum, in this case, might be a hole (on a product) or a protrusion. The CMMs precisely map these points and uses them to ensure that there is consistency from one part to another.

Translation

This refers to the process of determining the space between one feature on the product to another. To use the map analogy again, this is like moving from the river to the hotel and then on to a third point. In this movement, your starting point changes (from the river and then from the hotel). This shift of the starting point from one location to another is what is called translation. Going back to CMMs, the probe acts like your finger on the map and moves from one point to another on the surface of the product, essentially translating from point to point.

Rotation

Rotation is best understood by using the analogy of the map once more. When moving from one point to another, you will realize that not all points are located at right angles to where you are. What this means is that once you translate from the river to the hotel, you might realize that your third destination is not parallel to the hotel. If you were using a map, you would rotate the key to be parallel to your point of origin thus allowing you to measure the distance between your new point of origin and your next destination. CMM machines do this exact process when moving from point to point and measuring the distance from one datum to another.

These are just some of the terms that you may encounter when learning about coordinate metrology. All these terms refer to processes that make it possible for precision instruments like CMMs to measure product surfaces and ensure that parts conform to a very specific quality standard.

Although most people do not quite understand the role of quality control specialists in manufacturing processes, the reality is that they play a vital role in ensuring that we are all safe. For example, a vehicle part that is not manufactured to the correct standards could have serious repercussions for the driver of the vehicle if that part ever ended up in a car. Luckily, quality control specialists are able to ensure that for the most part, manufacturing processes adhere to the correct standards. To do these quality control checks, quality control specialists rely on a variety of tools and machines to do their job. Read on to learn about the various tools that are vital to this role.

Hand-held Tools

There are a variety of hand-held tools that quality controllers use in their work. These range from gages, slide-calipers, micrometers, and indicators. If you visit a typical manufacturing plant, you might notice quality control specialists randomly checking parts off the assembly line using these tools. Handheld tools offer great flexibility to these specialists, allowing them to walk around the manufacturing line and testing parts at different points of the manufacturing process. Another great benefit of these handheld tools is that they are easy to use and people quickly learn how to use them without a lengthy training process.

Fixed Coordinate Measuring Machine (CMM)

Coordinate measuring machines or CMM are machines that give a very precise measurement of surfaces by running a probe over the surface of the part. These probes can either be mechanical, laser or optical depending on the degree of precision that is required. These CMM machines are fixed thus are likely to be used at one point. This means that products being analyzed are likely to be brought to the unit unlike the hand held devises that the quality control specialist can walk around with. Fixed CMMs are very precise and can also be linked to data processing machines allowing quality control specialist to analyze quality control data across different periods and different production lines.

Portable CMMs

These machines go a step further and give quality control specialists the ability to move around with the CMM while at the same time enjoying the precision that comes with CMM. Portable CMM tools are however sensitive to environments where there are strong vibrations (such as manufacturing plants that use big machines) and thus cannot be used in all manufacturing environments.

3-D Scanners

3-D scanners offer greater precision and flexibility without any of the limitations that come with portable CMM machines. For example, 3-D scanners are not affected by vibrations or temperature variations and thus are likely to work in a wider range of manufacturing environments. 3-D scanners are also suited for complex manufacturing processes.

Quality control specialists rely on some or all of these machines to ensure that the manufacturing process continuously produces products that meet very precise specifications.

Air gaging is a common technique used in a wide range of manufacturing process. Technicians that work on the shop floor often utilize air gages due to the advantage that the product offers. Air gages are not only easy to use and fast, they can measure to very tight tolerances (down to a resolution of 5-50 millionths!) and even clean the part’s surface before measuring. When it comes to air gaging, most gage users automatically think of air plugs. There are, however, various styles of air forks and air rings. These tools provide similar benefits and a few additional ones too.

The Low-Down on Air Forks

In some cases, you can’t simply place a part in an air ring, e.g. on crankshafts. There are just too many journals and some of them have very tight tolerances. This means that there is no way to place an air ring over this area. This is when you will need an air fork.

You do not get air forks simply by slicing an air ring in half. There are some critical dimensions to consider. In addition, they come with precision-ground locating stops that are found at the back. These features allow the operator to create the reference based on the known part diameter and position the jets with precision.

Maximizing the Capabilities of Air Forks

You can get the air forks to really shine if it’s possible to customize the position of the air jets. For example, you can measure a diameter right up to a face by placing the jets near the end of the fork. Alternatively, you can also add multiple jets to measure up to three diameters simultaneously. You should be able to read the three diameters as one without a lot of computing power. Don’t forget to calculate shape and taper as well.

If you are measuring challenging outer diameters, it is a good idea to remove the mechanical snap or the bench stand and consider leveraging air.

The Low-Down on Air Rings

Air rings are the opposite of air plugs. They are typically utilized to measure outer diameters. These rings often have a basic design, e.g. a steel ring and a pair of jets attached to a particular location. Surprisingly, a lot of engineering is built into them.

If you need to calculate the size of the ring, ensure that you achieve a proper balance of clearance between the opening in the ring and the part. If there is too much clearance (it will measure a chord rather than the diameter), your readout will display a centralizing error. If you lack clearance, a geometry error can occur. In this case, you won’t be able to insert the part into the air tool.

You should check and ensure that the jets are positioned slightly lower than the body of the ring. It provides the air system with the correct differential characteristics to function properly. Additionally, it allows for ring wear.

Diameter Measurements with Air Rings

When it comes to measuring basic diameters, two-jet air rings will suffice. Gears and pullies, however, feature multiple ODs. In most cases, you will need to measure the diameter right up to the face where your rings are attached to. You will need to get a snout-type or shoulder-type air ring. They are basically blind hole rings that allow you to position the jets closely to the face and measure the outer diameter right to its end. Snout type rings can get around obstacles and clearances more efficiently. It is useful to note that air rings may be designed with between three and six jets.

A height gage is a measuring instrument designed to measure the height of a workpiece. It features a slider and measuring stylus. These components move relative to a measuring scale that is attached to a beam. They move along a single vertical axis, which is nominally perpendicular to a reference plane. That plane is typically fixed on the instrument base. Today, height gages are a valuable asset when it comes to quality control. If you are looking to get one, you have come to the right place. In this post, you will explore different types of height gages and learn how they work!

Option A: Electronic / Digital Height Gages

The first option that you can consider is a digital or electronic height gage. Digital versions of height gages are divided into three distinct groups:

• Group one: Height gages in this group often feature data output, floating zero, absolute zero, and metric/inch conversion.
• Group two: Height gages in this group come with all the first group’s features. The accuracy of the tool, however, is a magnitude of order better. They may also come with additional features such as probe compensation, TIR, max/min, ID/OD measurement, and tolerance setting.
• Group three: Height gages in this group have all the features that were mentioned in the second group. These gages, however, feature a higher accuracy rating. Most of them also have the ability to store and generate programs, motorized touch probes, air bearings, and computer interfaces (enabling SPC). You can use these height gages to measure a part feature in two dimensions. You just need to rotate the workpiece. Technicians can use gages from this group if they wish to reduce the demand on their CMMs and when higher accuracies are required.

Option B: Mechanical Height Gages

Depending on your company’s budget and needs, you may also consider mechanical height gages. This type of height gage has been utilized in flat plate layouts for many years. The three basic types of mechanical height gages include:

• Digital counter height gages: The readings are clearer than Vernier scales and often feature dual-digit and dial counters. These features help decrease the time needed to lay out a part. The dual-digit counters can be used as a floating zero or set at the reference datum.
• Dial height gages: These gages are compact in nature and are often available in sizes below 300 mm or 12 inches. If you are looking to get a personal height gage, this option suits you better. What’s more, it can be easily stored in a machinist’s toolbox.
• Vernier height gages: These gages can feature one or two scales on the beam (both metric and inch). Their main advantage over other height gages is their height! They are available from six inches to six feet in height.

Now that you have a better understanding of the available types of height gages and their features, it is time to get one! If you can’t decide on which height gage to get, do not hesitate to contact Willrich Precision for advice.

Both dial and digital indicators have contact points. What is a contact point? It is essentially the point of interaction between your part and your tool. It is one of the most important parts of an indicator and comes in a great array of types. Depending on your current needs, these contact points can be replaced or altered in various ways. Let’s find out more about the different types of points (varying by shape) that indicators have.

Air gages are instruments that are used to measure surfaces by ejecting a stream of air onto the surface, which is then read by sensing nozzles. These sensing nozzles then transfer the readings to a calibrated scale. Air gages are exceptionally good at measuring internal diameters with high precision. The display end of air gages has evolved over time and now allows for digital readings. Modern air gages also have data ports that make it easier to download or transfer of data to computers and other analytical machines for more precise readouts.

Air gaging tools are an important part of a Quality Management System (QMS). Air gages allow a manufacturing process to determine if the quality of products being produced meets set standards. Let’s find out how you can go about incorporating air gages into your QMS.

Gaging is a form of measurement where the object under study is compared against a set standard (a gage) and its precision determined by the extent of its deviation from the gage. This is a contrast to direct measuring where a tool simply measures the object in a direct reading process. There are different forms of gaging of which air gaging is one of them. Gaging works well in environments where a high degree of precision and speed is required. In general, gaging processes are faster than conventional measurement processes and yield a high degree of precision. Within the gaging world, different approaches to gaging are utilized depending on needs and requirements.