Reel-to-Reel Molding: Precision Assembly for Critical Applications

Specialized molding and assembly processes help companies to get precise results for industries like medical, aerospace, technology and general manufacturing. Multi-material molding and assembly processes require a good deal of complexity and attention to detail.

One of the most interesting modern solutions for complex assembly is called reel to reel molding, or also sometimes called strip molding.

This specific process helps to produce parts that are consistently crafted and bulk-assembled for precision. Experts in the field have discovered how using a reel to reel method evolves assembly from a traditional “loose-parts basis” to a process that is guided by the two reels for more precision and predictability. This is important for projects that require top standards, and benefit from these new processes.


Reel to reel molding processes involves two reels -- a feed reel that dispenses insert material, and a take-up reel that receives a finished product. A type of continuous carrier strip is fed through from one reel to another. With an injection molding process, plastic is molded over each individual piece or part as it gets fed from the initial reel to the final reel.

Continuous carrier strips can be made of different media. Sometimes metal stamping is used to help create the carrier substance. In other cases, assembly companies may use mylar tape or other media for a continuous carrier strip. A molded strip may also be used.


Some of the benefits of using a reel to reel molding process involves precise alignment and orientation for individual pieces. Because pieces are tethered to the reel, they are packaged and structured in a way that can facilitate better secondary processes. In the take-up reel, these pieces can be delivered in a way that facilitates easy final assembly.

By allowing for processes like in-line stamping, a reel to reel molding process expands what companies are able to do with linear production. Utilizing reel to reel molding can result in lower burdens of mold maintenance and less process error. This method can be useful in the production of OEM or high-design parts for specific industry applications.

There is also a level of consistency provided through the process of designing reel to reel molding assembly processes. For instance, it can be easier to view the pieces for consistency than it would be with a loose parts process. In line vision systems using cognex cameras can be set up to view and inspect both the incoming strip and finished insert molded product. This allows 100% inspection for critical dimensions with zero added labor or handling.

Also, with reel to reel molding, inserts are automatically loaded. The final product can be shipped on a reel, which makes it easier to use when it arrives at its destination. Some companies count on getting these types of parts deliveries to fit an agile secondary process involving putting the final pieces of a product or system together.

Reel to reel molding is often used for the sophisticated construction of electronic components. One excellent example is in the manufacturing of buses, where multiple individual parts need to be fitted onto a linear assembly. Parts may be held in place by different types of metal alloys for conductivity and placement. A reel to reel molding process allows the formation of these individual parts in a consistent way.

The same philosophy applies to other specific electronics gear -- for instance, semiconductors. At the semiconductor level, the process may be iterated on a much smaller scale, but the same principles hold true. In general, reel to reel molding has brought a high level of quality to electronics manufacturing. Along with processes like printed circuit board design that have enhanced how companies turn out device or component circuit boards, reel to reel molding provides a lot of advancement in connectivity for electronic parts and pieces that may be added to a hardware setup in a linear or sequential way.


Like other kinds of injection molding and assembly processes, reel to reel molding benefits from some general overall industry standards. Companies may apply ISO 9001 or other ISO standards to the process. Processes are also governed by standards from ASTM, and industry standards set or curated by trade groups like the Plastics Industry Association. All of these inform the process by which reputable and established companies offer molding services that work for clients.

In addition to build standards, processes like these may benefit from inspection standards that provide rules for identifying defects, and confirming the integrity of finished products. Some ISO standards may apply to the inspection process itself -- the best companies providing services like metal stamping and reel to reel molding understand these key standards and how to make their operations compliant through best practices. Although reel to reel molding adds functionality, these processes still have to be evaluated for precision. Engineers have to work to avoid small amounts of movement in parts production, such as a phenomenon known as “flash” and manage the demands of specific kinds of plastics. All of this requires a dedication to making sure that processes are as finely designed as possible, and looking beyond the surface when it comes to applying the principles that make reel to reel molding such a powerful technique for manufacturers.

Weiss-Aug is one of the established crafting, molding and custom assembly companies that has a track record for excellence. This industry leader provides custom parts for client companies in the aerospace, defense, automotive and medical fields, turning out consistently high quality results.