Plastic injection molding continues to become more and more sophisticated with part tolerances becoming tighter and tighter. Initially, tight tolerance was defined as +/-.002 inches and a very tight tolerance is +/-.001 inches. But today there are many factors that impact tight tolerance including part complexity and size, resin selection, tooling, and process conditions. So, getting the mold, part design, material selection and process correct is crucial when working with a product that requires tight tolerances.

Tight tolerances are essential when manufacturing complex parts, especially in the aerospace & defense, medical & life sciences, and diversified industrial sectors.  A few thousandths of an inch can be the difference between a component that fits and one that does not – if tight tolerances are not achieved properly the resulting products may underperform. So, it is critical that clients understand tight tolerances and their underlying objectives. Performance Plastics has parts in production that are +/-.0004 inches. Parts are measured in their Metrology lab with a CT Scanner.


Benefits of Tight Tolerances

There are many benefits to manufacturing parts with tight tolerances. It ensures that parts work together smoothly and fit as intended in their final form; parts mesh well and deliver enhanced functionality.   They produce lower failure rates and result in higher client satisfaction. Tight tolerances can also result in fewer post-molding processing requirements.  Additionally, tight tolerances allow for parts to be transitioned from metal to plastic, reducing overall weight and cost of the final product. This can be very advantageous in some industries, such as aerospace and defense.

Design for Tight Tolerances

Not every plastic injection molding project requires tight tolerances, and some organizations insist on tight tolerances for non-critical features.  Tight tolerance should only be required in instances where they are critical.  Many products require standard tolerancing because the consequences of failure are low.  As a general rule, designers should keep tolerances as large as possible while maintaining the desired functionality of the part.

Materials for Tight Tolerances

Additionally, material selection is a critical element in achieving tight tolerances.  Certain resins perform better under certain circumstances.  An experienced design engineer can guide a client in choosing the most affordable material that will deliver the best result.  So, it’s critical to bring in an experienced team early in the design process.

By engaging a production team during the design phase, part functionality, material selection and design can be discussed upfront, and the team can jointly develop a manufacturing process and correct materials that will produce high-precision components. It is crucial for organizations to partner with an experienced injection molder, who has expertise; the design and manufacturing teams should be integrated to allow manufacturability issues to be identified and addressed during the design process – thus saving significant time and unnecessary cost.

Establishing the right process and correct materials for each product and developing repeatability are key to manufacturing tight tolerance parts. While every application is different, there are some process and material conditions that impact tolerances. For example, quick cavity filling and uniform cooling at the desired temperature are conditions that are crucial to achieving repeatability, and thus, parts with tight tolerances.

Performance Plastics is highly skilled at designing and molding using high performance materials such as PEI-Ultem®, PAI-Torlon®, PEEK, and Fluoropolymers such as FEP, PFA, and PVDF.  We work with our customers to solve technically challenging problems.   We can propose materials to implement part functionality in the design stage of development. We offer manufacturing solutions such as a clean room, the ability to offer direct gating of fluoropolymers, high volume production, visual inspection, and automated facilities.

For more information and solutions, please contact Rich Reed, Vice President of Sales & Marketing at 513-321-8404 or email


At Performance Plastics, we understand that working with a qualified molding company is crucial to your company’s success.  It is vital to find a team to support your company’s mission and commitment to delivering quality products on time.  We have found over time, that there are three essential components that should weigh in your decision-making process when choosing a molder for your next application: Education, Trust and Quality.


Is your molding partner educated about your company and your products?  Do they understand your needs and goals?  Do they understand advanced materials and their properties?  Understanding resins and best molding practices including raw materials, drying time, heat history and molding temperatures will affect the outcome and quality of your application.


Trust is important in any business relationship – especially one that reflects on your business.  Do you trust your molding partner to properly do the job?  Open and continuous communication with key management of your molding partner is crucial to the success of any application.  Your team should keep you informed of market conditions pertaining to raw materials, new techniques, and opportunities for improvement?

Quality and Quantity

Quality and Quantity, both are important to your business.  Your customers rely on you for quality, dependable parts, but you must rely on your team for an on-time and dependable process.  Dependable processes, such as quality procedures, run rates and material quality control produce quality parts.

Performance Plastics, located in Cincinnati, OH has over 30 years’ experience molding tight tolerance advanced plastics such as Fluoropolymers (FEP/PFA Torlon, Peek & Ultem) for many industries.  We have developed proprietary processes enabling injection molding of parts that are thin walled, with tight dimensional tolerances, and complex geometries.

Education, Trust and Quality.  Think about these questions when choosing your molding partner. Remember – education, trust, communication, and quality of work are vital to a long-lasting business relationship. Ask the questions and get some answers. This will assist you in finding and maintaining a dependable partnership.

For more information and solutions, please contact Rich Reed, Vice President of Sales & Marketing at 513-321-8404 or email

As you’re designing and manufacturing your next application, wouldn’t it be ideal if you could analyze all the parts, compare them to the original drawings and get results quickly, without damaging your samples? At Performance Plastics, we offer the services of industrial computed tomography (CT) scan. This provides us the ability to measure all aspects of your part, without having to damage it.

Industrial CT scanning in the design process gives you access to the inner workings of a part without having to destroy the original. The scanner rotates the part 360 degrees and uses X-rays to create a precise 3D model. This allows for a thorough analysis of object dimensions, porosity, wall thickness, assembly defects, comprehensive comparisons, and reverse engineering.

The CT scan can then be compared to the CAD model and to other parts. In addition, it can easily analyze surface variations and provide cross sections to reveal hidden features.

Performance Plastics now offer a variety of CT scan-related services:

  • Part-to-CAD comparisons create a precise overlay of the scanned part to the original 3D part model database
  • Part-to-part comparisons provide an overlay of two scanned parts to reveal dimensional deviation
  • Void and inclusion analysis provide material and defect analysis showing void or inclusion size and locations
  • Wall thickness analysis measures slight changes in the wall stock of complex parts without destructive testing
  • Dimensional analysis provides full article inspections and reporting
  • Reverse engineering capabilities that generate a 3D CAD file

Performance Plastics, located in Cincinnati, OH has over 30 years’ experience in molding tight tolerance advanced plastics such as Fluoropolymers (FEP/PFA Torlon, Peek & Ultem) for many industries.  We have developed proprietary processes enabling injection molding of parts that are thin walled, with tight dimensional tolerances, and complex geometries. For more information and solutions, please contact Rich Reed, Vice President of Sales & Marketing at 513-321-8404 or email

Performance Plastic’s  Metrology Lab focuses on advancing measurement science through our ability to understand all aspects of your part.  Mechanical Engineer, Jordan Murray, dives into our industrial computed tomography (CT) Scanning process, explaining the benefits of CT Scanning and how it helps us to solve your problems.

To learn more about Performance Plastic’s CT Scanning process contact Rich Reed, our Vice President of Sales and Marketing, at (513) 321-8404 or

Proprietary Tool Design Software Contributes To Precise Sealing Surface

  • Market: Oil & Gas
  • Project Requirement: Produce an “out-of-mold” net shape fiber reinforced PEEK seal holding dimensional tolerances of .0003 inches.


Mating parts providing a fluid or gas seal are critical components in most mechanical systems. We commonly think of them in valves and connector assemblies, but they are also found in pressure vessels, compressors, pumps, motors, engines, transmissions, and almost all mechanical power trains. Seals, especially those that mate to moving parts, have a demanding set of quality requirements. Each application has its own specific needs, but all seals are characterized by tight dimensional tolerances and excellent surface finish.


compressor valve plate with thermoplastic seals

Dresser-Rand is among the largest global suppliers of custom-engineered rotating equipment solutions for long-life, critical applications in the oil, gas, chemical, petrochemical, process, power, military, and other industries worldwide.  Their industry leading Magnum™ valves are used in all brands of reciprocating compressors, where they are known for operating at high compressor speeds and pressure differentials. The product contains 30 to 100 valve elements manufactured from a fiber reinforced PEEK thermoplastic, providing the high strength and low inertia necessary for reliability at high operating speeds.



Dresser-Rand engineers wanted to improve the usable life and leakage profile of their Magnum valve without absorbing any increase in component cost.  The sealing surface specifications were tightened to 0.0005 inches (12.7 µ) which was key to accomplishing the performance improvements.

thermoplastic sealing valve

Dresser-Rand’s then current supplier of this component was unable to meet the more stringent sealing surface dimensional tolerances “out of the mold” necessitating a finish machining operation to bring the part into tolerance.  However, machining the sealing surface removed the resin-rich surface of the part creating micro-cracks in the surface and exposing reinforcing fibers. Both of these unavoidable consequences of machining negatively impacted component performance, useful life and cost. While it’s never easy to get “something for nothing”, Dresser-Rand knew the right people to talk to, the injection molding thermoplastic experts at Performance Plastics, LLC (PPL).


Performance Plastics knew eliminating the machining operation would improve strength, reduce trapped impurities, and lower manufacturing cost.  Thus, PPL’s engineering team focused on producing a “true net shape” part directly out of the mold.   Key to accomplishing the customers goals involved leveraging the Company’s proprietary, iterative tool design process.  It required making a 3D CT scan of preliminary molded parts measuring, in this case, approximately 1 million critical part dimensions.  This analysis identified minute distortions.  Utilizing internally developed proprietary software, PPL integrated the CT scan data with CAD/CAM software to make exacting mold modifications eliminating the out of tolerance conditions.  This process contributed to producing a best in class “out-of-mold” conforming part.

The manufacturing process also had to be optimized to produce the desired performance results.  Although the material posed molding challenges, PPL decided to direct gate the part at the top to ensure symmetry of material flow throughout the cavity, critical in achieving roundness to the sealing surface.


The results of development program surprised everyone. PPL achieved “out of mold” net shape parts with a seal surface capable of meeting sealing ranges of 100 psi to 3,000 psi, with no porosity and consistently meeting dimensional tolerances of 0.0003 inches, or 7.62 µ. Eliminating the need for subsequent finish machining dropped the leakage rate for the valve by 50%, from 1.0 scfm to 0.5 scfm. At the same time, Dresser-Rand reported a doubling of estimated lifetime from 10M to 20M cycles between valve element replacement. Lastly, PPL’s direct gating approach improved material efficiency, by eliminating the sprue and runner system, resulting in a lower price per part.  Dresser-Rand’s customers benefitted from improved performance, increased service life and lower maintenance costs.

For more information about our net shape molding process please contact us.