Understanding Accuracy, Precision and Tolerance to Improve Product Design

Posted On: November 25, 2019

A product design is about visualizing, understanding customer requirements, and what they need in the product. It is the most important stage in the manufacturing process because the actual manufacturing and production really depend on the accuracy of the design. In the manufacturing sector, CNC machining has long been used for fabrication and production. With the advent of technology and computer-aided design software, designing a product may has become easier, however, it has made the design as such more complex than before. In the design stage itself, you need to set the standards for accuracy, precision, and tolerance of the product. This post elaborates on the significance of these three aspects to improve product design.

Exact Meanings of Accuracy, Precision, and Tolerance in Manufacturing

Today, various software programs are used in conjunction with CNC machines to produce accurate circuit diagrams. However, the actual parts are made by machines which may or may not be automated. So, the question here is how close we can come to achieving the level of accuracy and precision in the software-aided design. The following points will help you understand it better.

• Accuracy:

  Every organization follows its own set of standards or benchmarks. Additionally, they need to comply with the standards set by official bodies or governmental organizations. In this case, accuracy can be described as the degree to which a player can conform to the known or set standard or value. When we talk about the accuracy of CNC machines with respect to the computer-generated design, it means if according to the design the length of the metal workpiece is 20 mm, then an accurate CNC machine would get as close to 20 mm (perhaps with a difference of +/- 0.0001 mm) without any other error.

• Precision:

  Consistent repeatability is what precision means when producing multiple parts with the help of a CNC machine. It is easy for CAD tools to produce and repeat the required precision as many numbers of times. However, for manually controlled machines, this is a challenging aspect as human errors are bound to happen no matter how good the workmanship. Consider a shooting range, where you need to repeatedly need to shoot at the same point, and it may or may not be the bull’s eye. But, hitting that same point is important. This is what repeatability and consistency mean when the highest level of precision is required to be achieved.

• Tolerance:

  We can safely say that tolerance balances out extreme precision and accuracy. What this means is any machine or object has a certain degree of vibration in it. So, all of them will never be exactly alike and will have a certain amount of variance in the values of precision and accuracy. Tolerance paves way for that acceptable amount or limit of deviation or variance in each part produced. An accurate computer-aided design will keep room for this subtle variance. The acceptable value of tolerance would really depend upon the application.

Factors Influencing Accuracy Levels of a CNC Machine

Once a CNC machine is installed, getting control over some of these factors is difficult. Here are some factors which may influence the CNC machine’s accuracy output:

• Weather and Environment:

  Although machines are designed to work in harsh environments and extreme temperatures, this factor may minimally affect the accuracy levels. As far as possible, position them in locations with ambient temperatures and tolerable humidity.

• Tool Calibration:

  Repeating calibrations at regular intervals is a crucial factor to understand pitch error and backlash compensation, even if it is done initially.

• Machine Condition:

  Machine health monitoring is a key aspect. Preventive maintenance is essential to know the machine condition and fix damages if any.

• Wear and Tear:

  With continuous use, any machine undergoes wear and tear, and the same applies to the tools used. It is essential to fix the diminishing cutting edges and the changes in internal surfaces.

• Damaged Tools:

  Replacement of damaged tools, as and when required, helps prevent mishaps and maintain the required accuracy levels.

Are you looking for CNC machining and tool making services for the parts in your application? There are many players who offer services pertaining to CNC machining. However, it is essential to partner with a player who offers precision and can understand your requirements relating to the products or components. BDE Manufacturing Technologies offers all kinds of CNC machining services and is totally focused on achieving the required quality and precision

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