Dimensional Measurement Blog

In order to obtain an engineering degree, you must learn certain concepts and skills in school. However, developing an engineering career means your education continues on the job. One field not typically taught extensively in engineering school is metrology, but for any engineer entering the field of manufacturing, understanding metrology is essential. 

In the simplest terms, metrology is the science of measurement. In practical terms, when it comes to manufacturing, engineers have a vested interest in knowing the fundamentals of geometric dimensioning and tolerancing, commonly referred to as GD&T. Engineering drawings and 3D CAD models use GD&T to communicate engineering dimensions and tolerances to manufacturing and quality staff. If the engineer doesn't know how to effectively communicate in the language of GD&T, the finished product will likely not meet the desired outcome.

Why Understanding Metrology Is Important

The purpose of engineering design is to convey information in a way that makes it as easy as possible for the manufacturing team to create the desired parts and assemblies. A good engineering drawing will consider:

• The design intent
• The people and processes involved in manufacturing
• The inspection and verification process

The consequences of not understanding the fundamentals of GD&T can be dire:

• Disruption of manufacturing schedules
• Damaged reputations because of the inability to fulfill requirements
• Inability to meet budgets

Because metrology is so important in the manufacturing industry, there are several benefits for young engineers to learn it sooner rather than later:

1. Quality - Good engineering drawings result in parts that match the design intent.
   
   
2. Budget - Getting a drawing right the first time saves money.
   
   
3. Time - When dimensions and tolerances are stated clearly and thoroughly, manufacturers do not need to take the time to ask questions or get clarification.
   
   
4. Customer satisfaction - Producing the correct results in a timely manner keeps customers happy.

So how does a engineer learn more about GD&T if it's not commonly part of the standard curriculum? The American Society of Mechanical Engineers (ASME) offers the Y14.5 - 2009 Dimensioning and Tolerancing specification. This set of guidelines describes the language of GD&T and establishes uniform practices for communicating the requirements on engineering drawings. Additional resources include training programs and traveling seminars.

Q-PLUS Labs offers both training and consulting services to help ensure that your manufacturing process goes as smoothly as possible. Our training programs are designed for small groups across multiple disciplines so that engineers, manufacturing staff, and other key players can learn how to most effectively communicate in the language of GD&T. Contact us today to learn more about how we can help you.

Are you an engineer in the field of manufacturing? Tell us in the comments section how you learned about GD&T.

 

There are many ways to inspect an object. You can use high-tech machinery, precision hand tools, and even the human eye. Every inspection method comes with strengths and weaknesses, and each application will work better with some methods than with others. Understanding these strengths and weaknesses can help you decide which types of inspections work and do not work for your specific application.

Visual inspection is perhaps the original method, and it is still often the first line of defense in inspection and verification processes. The eye is a powerful inspection tool mainly because it is connected to a human brain that possesses information and skills that machines do not. However, the eye can be tricked, so knowing its limitations is important.

The Strengths of Visual Inspection

Almost all manufacturing applications should include visual inspection at some stage of the process for these primary reasons:

• Save money - If there is an obvious flaw that can be seen by the naked eye, there is no need to take the time and resources to continue the inspection process.
  
  
• The human element - Dimensional inspection evaluates just that: the dimensions. But what if the object produced is a mirror image of the intended result? This could be overlooked in an open setup or a non-model-based CMM inspection because the dimensions might exactly match the specifications. However, a visual inspection to compare the final product with the engineering drawings would quickly show the mistake.
  
  
• Evaluate workmanship - Certain types of dimensional inspection equipment measure the edges of an object but not the surfaces, or vice versa. Take the example of a cube. Your CMM might confirm that the surfaces of the cube are the correct dimensions, but it might not detect a large gash on one of the edges. Visually inspecting parts can help ensure that all of the specifications are met, not just the ones the equipment can see.

The Weaknesses of Visual Inspection

Although the human eye is a sophisticated tool, it can also be easily tricked. Consider some of these weaknesses associated with visual inspection:

• Unreliability - Browse through these optical illusions to get a sense of just how unreliable the human eye can be. This does not mean that visual inspections are always unreliable, but that they shouldn't be your only method of inspection.
  
  
• Imprecision - The human eye is not capable of making precise measurements, especially on a very small scale. Even when comparing two similar objects, the eye might not notice that one is slightly smaller or larger than the other. This concept also applies to characteristics such as surface roughness, size, and any other factor that needs to be measured.

Clearly, visual inspection comes with advantages and disadvantages but the value of it should never be quickly counted out. The best approach to effective dimensional inspection is one that includes multiple methods. Q-PLUS Labs is here to help you decide which dimensional inspection approach is right for your application. Contact us today to schedule a consultation.

 

Dimensional inspection is used in a broad range of industries for a wide variety of applications. However, there are some common reasons why this type of measurement is used. Whether the objective is to compare a prototype to a drawing or to ensure that a finished product meets certain standards, the fundamentals of dimensional inspection remain the same. Highly accurate measurements are taken to determine how closely an object matches its originally intended dimensions.

In general, if dimensional measurement is required, the results must be both accurate and precise. Although multiple techniques and countless applications exist, there are four main categories of dimensional inspection.

Four Common Dimensional Inspection Applications

1. First article inspection. Implementing a manufacturing process requires extreme attention to detail, especially if the process is new or if the equipment has been specially designed. First article inspection is required to ensure that the equipment was properly installed and calibrated, and to verify the manufacturing process. Dimensional measurement is used to compare the first objects from the manufacturing line to 3-D CAD models or other specifications.
2. Quality control. When objects coming off a manufacturing line must meet certain quality standards, measurement equipment is used to confirm that the dimensions fall within the required tolerance levels. In some cases, when the tolerance levels are more rigorous, each object is measured automatically. In other cases, batches might be spot-checked for quality.
3. Regulatory compliance. In industries for which regulatory compliance is necessary, dimensional measurement ensures that the required specifications are met. Regulatory bodies such as the FDA or FAA often have requirements regarding the dimensions of certain components. 
4. High-precision engineering. When creating a larger assembly from smaller parts, high precision is often required. If a minor flaw or inconsistency can impact an entire process, ensuring that such imperfections do not exist is critical. 

Employing dimensional measurement in these scenarios offers many benefits, including reduced liability, improved quality, and lower costs.

If you need dimensional inspection services for your business, contact the professionals at Q-PLUS Labs. We provide outsourced measurement services for a range of industries including manufacturing, aerospace, medical, and more. Schedule a consultation today to learn more about how we can help you with your dimensional measurement needs.

How does your company use dimensional inspection?

 

Purchasing dimensional inspection equipment requires making a big decision, and in most cases a significant financial investment. It is important to be certain that the equipment you buy will serve its intended purpose and provide the results you need.

Because there are so many different types of equipment that can be used for a broad range of purposes, it helps to know what questions to ask before you buy.

11 Dimensional Inspection Equipment Questions You Need to Ask

1. What sensor type do you need?
   
   Depending on the surface characteristics of the objects you intend to measure, you may need either a contact sensor or a non-contact sensor. Within each of these two categories are several other options and different sensor types. The more you know about the objects you will be measuring, the better able you will be to select the right types of dimensional inspection equipment.
   
   
2. What tolerance levels are required for your application?
   
   There is a big difference between replicating an antique to sell in a gift shop and mass producing components that will be used in a medical device. In the former case, a certain amount of inaccuracy is tolerable, while in the latter case the requirements are more stringent. Make sure you know how precise you need to be, especially if you have to maintain regulatory compliance.
   
   
3. Does your equipment need to be portable?
   
   Do you need a machine that will always sit at the end of a production line, or do you need a more portable unit that can take measurements in the field?
   
   
4. What size(s) are the objects you need to measure?
   
   Some objects are small enough to be put into a machine, while others are simply too large or heavy. On the other hand, objects that are on the nano scale will require specialized equipment.
   
   
5. What shape(s) are the objects you need to measure?
   
   Does your object have internal geometry that you need to measure? Bore holes, threads, and other complex geometry cannot always be measured by certain types of dimensional inspection equipment or without certain accessories.
   
   
6. How fast do you need results?
   
   Measuring the occasional prototype is a different scenario than inspecting every component that comes off a production line. It is important to know how quickly you will need results so you can purchase a machine that is capable of meeting your needs.
   
   
7. Does your equipment need to be automated?
   
   Some dimensional inspection equipment can be automated, but not all of it can be. If this is an important factor for your application, make sure it is a high priority in your purchasing decision.
   
   
8. Who will be using the equipment?
   
   Ease of use should be considered if you are weighing multiple options. Will you need to hire new staff or train employees to use this new equipment? Does your budget support that?
   
   
9. What is required to maintain the equipment?
   
   High-precision measurement equipment needs to be properly set up, regularly maintained, and periodically calibrated. Does your staff have the skills to do this, or can you outsource it?
   
   
10. How durable and reliable is the equipment?
    
    Dimensional inspection equipment is an investment. It is important to compare multiple manufacturers and work with an expert who has experience will all of them.
    
    
11. What is your budget?
    
    Perhaps one of the most important factors is your budget, however, be sure to weigh all of the above before you make a decision.

If you would like to learn more about selecting the right dimensional inspection equipment for your application, download our free guide. You can also schedule a consultation with one of our dimensional inspection experts who can walk you through the entire process. Contact us today to schedule an assessment.

What type of dimensional inspection equipment are you looking for?

The simplest solution is often the best. This old adage applies to almost anything, including dimensional inspection. In a room full of high-tech equipment like 3D scanners, coordinating measuring machines, and high-precision devices that can measure on a nano scale, sometimes the only thing really you need is a pair of calipers.

Dimensional inspection hand tools are sometimes the best answer when you need to take measurements. They are both portable and precise, are generally cost-effective, and they can be used for a broad range of applications.

10 Types of Dimensional Inspection Hand Tools 

1. Calipers - There are several different types of calipers designed to measure length, depth, internal, and external dimensions. Calipers can also be used to transfer dimensions from one object to another.
2. Bore gages - Take an internal diameter measurement or compare to a pre-determined standard.
3. Fixed gages - Used only to compare an object to a standard, fixed gages can measure attributes such as angle, length, radius, bore size, thickness, and other parameters.
4. Micrometers - These dimensional inspection hand tools can use mechanical, digital, laser, dial, or scale technology to precisely measure length, depth, thickness, diameter, height, roundness, or bore.
5. Protractors - Measure angles with a variable protractor or compare the angle of an object to a standard with an angle gage.
6. Indicators and comparators - The precision movement of a spindle or probe is amplified so the results can be displayed digitally or on a dial or column.
7. Air metrology instruments - Thickness, depth, diameter, roundness, taper, and bore can be measured by calculating changes in pressure or air flow.
8. Ring gages - Typically used as a pass/fail test, ring gages can be threaded, smooth, or tapered to test the size of pins, threaded studs, and shafts.
9. Length gages - Electronic or mechanical, these devices are used to measure or compare the length of an object.
10. Thread gages - The spacing, shape, size, and geometry of a thread can be verified or measured with a thread gage.

Although dimensional inspection hand tools are frequently a simple and elegant solution, they still must be treated with the same care as a machine that uses more advanced technology. Some devices must be calibrated or regularly cleaned to ensure that they provide consistent, accurate results. It is also important that the operator is appropriately trained to prevent human error.

Whether you have a simple measuring problem or a complex quality control requirement, come to Q-PLUS Labs for all of your dimensional inspection needs. We'll help you select the right equipment and either train your staff to use it or perform the measurements in-house. Want to learn more about selecting the right dimensional inspection equipment for your application? Download our free e-book today.

Which dimensional inspection hand tools have you used?

 

For some dimensional inspection applications, the best way to obtain measurements is by using a sensor that comes into contact with the object. Contact sensors work best when the object is rigid and not fragile. They are also often used when the surface of the object does not lend itself to light sensors because it is reflective or too dark.

3 Types of Dimensional Inspection Contact Sensors

If your application does lend itself to a contact sensor, the three primary options are:

1. Coordinate measuring machines - Also known as CMMs, these mechanical systems use probes to measure the surface characteristics of an object. The physical measurements are converted by a transducer into electrical signals that are then analyzed by specialized software programs. Basic models provide XYZ readouts, while more advanced technology can work with CAD models and can be fully automated. CMMs are often used for first article inspection or quality control.
   
   
2. Articulating arms - These are basically portable CMM systems that are not limited to the linear X, Y, and Z axes. Because they can move on multiple axes of rotation, articulating arms are often used when the object has cavities or other geometry that limits the accuracy of a traditional CMM. They are also useful when an object must be measured in the field.
   
   
3. Form and contour tracers - For small objects or those with very tight tolerances, form and contour tracers use a stylus with continuous contact on the surface to measure features such as edge radii, thread forms, roundness, and cylindricity.

There are several other types of contact sensors, and even more types of equipment within each category. If you're not sure what type of equipment will produce the desired results, it's best to work with an experienced professional. Contact sensors do not work well for dimensional inspection when the object is soft, elastic, or extremely small. In these cases, non-contact sensors are generally the best option.

Q-PLUS Labs is here to help you decide what type of dimensional inspection equipment makes the most sense for your application. To learn more, download our free guide, or contact us today to schedule a consultation.

What type of contact sensor do you think would work best for your dimensional inspection needs?

Dimensional inspection can be performed with a wide variety of methods and equipment, depending on the object being measured. When selecting equipment, remember the cardinal rule of dimensional inspection: The object being measured cannot be altered during the measurement process. This means that some objects cannot be touched because the resulting measurements will be inaccurate.

When touching an object with a probe will alter its dimensions, non-contact sensors must be used during the measurement process. Cases when this is appropriate include when the object is:

• Soft
• Elastic
• Very small
• Fragile

Examples include objects such as micro-gears, rubber gaskets, prosthetics made of soft plastic, or a fragile antique with a delicate surface.

Non-Contact Sensors for Dimensional Inspection

Several types of non-contact sensors can be used for dimensional inspection, including:

• 3D scanners. There are two main types of 3D scanners: those that use structured light and those that use lasers. In both cases, light is projected onto the surface of an object and measurements are made based on the reaction of the light. With structured light, the distances are measured using the distortion of pixels, and with lasers, the reflection is used to triangulate distances. Clearly, the surface characteristics are a significant factor in determining whether 3D scanning should be used.
• Optical comparators. When light is projected onto an object, its resulting shadow or silhouette can be used to take measurements or compare the shape to the specifications. Fiber optic technology can also be used for edge detection.
• Vision systems. This type of equipment uses a similar concept to optical comparators in that light is projected onto a screen. However, vision systems also use cameras or zoom optics to relay an image to a display. Other accessories such as edge detection, touch probes, other types of sensors, and automation technology can also often be integrated into these systems.

If you're not sure what type of dimensional inspection equipment makes the most sense for your application, working with an expert is best to ensure accurate results. Q-PLUS Labs provides in-house or on-site dimensional measurement services for virtually any industry or application.

What types of objects do you need to measure? Do you think that using a non-contact sensor is the best approach?

3D scanning can be used for a broad range of applications. For example, you might want to create a replica of an artifact or inspect a sand casting to a 3D CAD model. However, not all dimensional measurement applications warrant the use of 3D scanning. In some cases, a different or simpler approach might be appropriate.

So how do you know when not to use 3D scanning? If any of these three applications are similar to yours, you might want to re-evaluate your approach:

1. You only need to measure one dimension - The whole point of using 3D scanners is to measure objects in three dimensions. If you only need to know the length or width of an object, a simpler (and less expensive) measurement system or gage may suffice.
2. You need an extraordinarily high level of precision - certain high-end 3D scanners have the ability to produce very precise results, but some applications call for an immensely high degree of accuracy and precision. If you are measuring the profile of a ground cam or a high-speed gear, a non-contact 3D scanner will not likely be a viable solution.
3. Your object has interior surfaces that cannot be seen - If you can't see a given surface, an optical 3D scanner can't see it either. In these cases, a contact probe can often reach the geometry of interest such as a bore hole or other interior surfaces. In other cases, however, sectioning or slicing of the object may be required. CT scanning is also a possible solution however this method has several limitations of its own.

Fortunately, 3D scanners are just one of many tools in the dimensional measurement toolbox. Other types of measuring devices you can use include:

• Direct computer control coordinate measuring machine (DCC-CMM)
• Optical video probes and comparators
• Contour and form testers
• Reverse Rapid Prototyping system (CGI)

This short list represents just a few of the options that might be useful for your dimensional measurement applications. The best way to determine what type of equipment best matches your needs is to work with a qualified dimensional measurement service provider that has the experience and expertise to help you decide.

Q-PLUS Labs provides 3D scanning and a range of other dimensional measurement and inspection services, so no matter what measurement problem you are trying to solve, we can help. Contact us today to schedule a consultation.

What projects are you considering for 3D scanning? Might another measurement method provide the results you need?

3D scanning can be used for a broad range of applications, some of which you might not expect. It can be employed in any situation where the size, shape, and surface characteristics of an object are important. Advances in the technology have further broadened the scope of its utility. It is possible to measure geometry with greater accuracy as well as to capture small details that were previously not possible to measure.

The purpose of 3D scanning is to capture surface geometry, but the reasons you might want to do this can vary significantly. Some of the most common applications include:

1. Reverse engineering and protoyping - There are many reasons that one might want to replicate an object through reverse engineering, and 3D scanning is one of the most effective ways to create an accurate representation of the original object. The level of accuracy required can also vary depending on the application, so it is important to understand the objectives for reverse engineering.
2. Manufacturing quality control - In many cases, parts coming off a manufacturing line must meet specifications within a certain tolerance range. 3D scanning can be used to accept or reject products for quality control, and to ensure that mass-produced parts are able to fit together properly and consistently.
3. Industrial metrology - A highly detailed 3D representation of a machine part can be used to evaluate wear patterns, confirm the final build, and analyze other complex surfaces. It can also be used to replace old parts that do not have an existing CAD model.
4. Medical applications - Teeth, bones, and even skin surfaces can be modeled using 3D scanner equipment. This information can be used to create prosthetics, orthotics, and other medical devices.
5. Movie production - The entertainment industry uses 3D scans for visual effects and other 3D graphics. This technology is also commonly used for video games and animation. View our 3D scanning gallery to see how 3D renderings of people and other objects can be generated.
6. Artifact documentation - Archaeologists and other scientists can use 3D imaging to create replicas of unique artifacts and other materials of interest without damaging them. The scans can also be used for modeling, documentation, and restoration.

The type of 3D scanning equipment you select depends on the application and a number of other factors. Choosing the right equipment early in the process can help you save money and produce the best possible results. Q-PLUS Labs is here to help you select the right equipment, or you can outsource some or all of your 3D scanning needs directly to us. Contact us today to learn more or to schedule a consultation.

What 3D scanning applications have you used in your business?

 

Reverse engineering can be used for a broad range of applications, from precisely duplicating an airplane part that is no longer manufactured to making a mold to replicate an antique statuette. The type of reverse engineering required will depend on the specific application and the necessary degree of precision. Knowing these factors in advance can help you determine the type of reverse engineering that makes the most sense so you can get useful results and make the appropriate budget decisions.

Exploring two extreme ends of the spectrum illustrates the difference between reverse engineering types and why it is important to understand them.

Case 1: Precision is important

Various factors are considered when determining the best method for reverse engineering. Take the example of an aircraft part or biomedical device. You have the original part, but no design specifications. In this case, the following factors are considered:

1. Original object - Because having a high degree of precision is important, several original parts are required to generate the most accurate duplicate part. These several parts will be measured and compared; the average measurements are typically used to replicate the part.
2. Tolerance - This represents the range of measurements that are acceptable. When working with a regulatory body such as the FAA or FDA, you generally must stay within a certain allowable deviation.
3. Accuracy - A high degree of accuracy is required to meet the desired function of the part.
4. Measurement approach - Many types of measurements using various contact and non-contact sensors will be taken with either a low-density ordered data or high-density data approach, possibly with millions of points to get the most accurate and detailed information possible.
5. Purpose - You may want to create new tooling or parts for a high-precision application, or duplicate a part for which you do not have existing specifications. The result might be parametric CAD models, 3D mesh files, or engineering drawings that can be used for manufacturing.

Case 2: Precision is less important

When replicating an object that is not subject to regulatory scrutiny, a less strict approach can be taken. The same factors apply, but they are handled differently:

1. Original object - Generally only a single original object is required.
2. Tolerance - The tolerance levels may not be important at all, making the measurement requirements significantly less onerous.
3. Accuracy - The original object may have a more free-form geometry that does not require the same degree of accuracy.
4. Measurement approach - Only 3D scanner measurement data may be required to generate a suitable duplicate and engineering drawings are generally not required.
5. Purpose - You may want to get a digital representation of a product for a marketing video or reproduce products for manufacturing. The result might be a 3D mesh or non-parametric CAD model that can be sent to a rapid prototyping machine and also allows you to compare reproductions to the original.

Of course, there are a broad range of examples that fall between these two ends of the spectrum. A good reverse engineering lab can help you determine which reverse engineering approach is right for your project.

If you need reverse engineering services, contact the experts at Q-PLUS Labs. We provide 3D scanning & digitizing, precision CMM measurement, 3D CAD modeling, and engineering drawing services to help you reverse engineer any type of part. Contact us today to learn more about our services.