What to Expect Regarding Lead Times Associated with Plastic Injection Molding

You’ve been given a new project to source that includes some plastic injection molded parts. If you don’t have a molding supplier (or if you’re not happy with the one you have, and this is the perfect opportunity to find a new one), it’s time to start doing a little research. While you certainly can find potential providers out there, just how long will it take for the bidding process? Once a contract is awarded, how long until the mold building can begin, and how long should you expect it to take until you get samples to inspect? After samples are approved, what kind of timeframe until the tooling is production ready? And, once the molds are complete, how long should it take to get parts?

Of course, all manufacturing programs are different, so each will have unique elements and will take varying amounts of time. Additionally, your company may have some specific sourcing requirements that vary from a standard approach, in which case the number of necessary steps, as well as the tasks within and timing of each, will be affected. Nevertheless, while the descriptions contained in this article are mostly estimates and generalizations, we can touch on the main points and walk through the process, so you have fairly accurate and reasonable expectations for each stage.

In addition, the research and development (R&D) phase of a new project can be very complex and literally take years. As such, we will begin with preparing for the bidding process and leave a discussion about R&D involving injection molding for another time.


The search for a potential supplier can take months, possibly longer, depending on the complexity of the project. Finding the right molder with the necessary experience, qualifications, resources and offerings who is a good fit for the program and for your company generally takes some time. Unless you’re pressed for time (obviously not ideal), expect it to take a few months to make a somewhat lengthy list of potential molders and then a week or two to review the candidates internally and to whittle it down to your short list.


To be as efficient as possible, it’s a good idea to start compiling the data and materials needed to create a detailed and thorough request for quote (RFQ) package while the sourcing research is being conducted. Performing both activities concurrently can save time, when and to the extent it is practical to do so.

Further, the investment required for tooling used in plastic injection molding can be significant. Thus, it is well worth the time and effort to review all relevant factors when preparing an RFQ and making sure it includes all the essential elements. Accordingly, just gathering the necessary items can take weeks, as will creating the production files and drawings, if they don’t exist, although we will assume they do for this discussion. Then, it can take days or even weeks (depending on the project’s complexity) to draft an organized request, including all applicable information, summarizing the project, etc.


Although making plastic parts might seem fairly straightforward to some, modern mold building, scientific injection molding, and professional quality control procedures involve multiple disciplines and require a significant level of expertise to perform properly. As such, preparing a thorough and accurate proposal for building molds and/or manufacturing parts should involve reviewing and analyzing quite a bit of data and collaborating with the customer to customize the approaches taken in order to optimize the program. Therefore, it should take at least a week for a good supplier to bid on a job, but it can take a month or two depending on the complexity of the project.


An important element of building an injection mold is performing a Design for Manufacturability (DFM) study on the parts to be manufactured. A DFM study analyzes the design of a part with the intent of optimizing the quality of the part and the efficiency of the manufacturing process. Performing the study with the proper software and then reviewing the study report with the customer generally takes about a week. If the DFM study identifies anything other than minor recommended design changes, the time needed to make major adjustments often takes weeks. Subsequently, another DFM study may be warranted, further design changes made, etc.

After the part design is finalized, most tool builders prepare a mold design based on the approved DFM report and review the mold design with the customer. This often takes a week or more.


Once the DFM study report and mold design has been approved, the building of the mold can begin. This includes purchasing materials and performing the actual CNC work, EDM, milling, assembly, etc. Of course, the time before work actually starts depends on the lead time for receiving materials and on the mold builder’s schedule. Generally speaking, fabricating a custom plastic injection mold will take a minimum of three months, although the time varies greatly depending on the complexity of the mold. Single cavity tooling without side action can take a little less time, while multiple cavity molds with slides or other mechanical elements can require a much greater period.


Once the fabrication work is complete and the mold has been assembled, the builder will perform the mold qualification testing to confirm the dimensional accuracy of the part and to validate proper mold function. Once parts produced during this process meet the dimensional requirements, these “tooling samples” should be provided to the customer along with an inspection report. The mold qualification stage, as before, depends on the builder’s schedule, although it often takes about a week or two, assuming adequate planning.

If the samples are not approved, the mold needs to be disassembled and modification work is performed. Alternatively, the parts may be conforming but some issue exists, so a part design change might be needed. That could take a significant amount of time, depending on the work required to be performed on the mold, which might be quite a bit and possibly entail ordering new materials, even for seemingly minor design changes.

Subsequently, the mold is reassembled, retested and more samples are produced. The modification work and another round of testing generally takes at least a couple of weeks, although it depends on the severity of the changes needing to be made. Also, if more materials need to be ordered, that could delay things a bit further based on the material supplier’s lead time.


As soon as the tooling samples are approved, the builder can perform any remaining work on the tool (e.g., polishing, mold labeling), prepare it for shipment (assuming the builder and the molder are different), and then ship the mold to the molder. Expect that finishing work and prep time to take around two to three weeks. The actual time it takes to ship the tool to the molding supplier depends on the distance traveled. A safe estimate for a shipment from overseas is about a month, plus outbound customs at the place of origin and inbound customs in the US often take about a week each.


Once the tool hits the molder’s dock, they generally perform an inspection, clean the mold (builders usually apply some type of anti-rust grease, when traveling over water), and prepare it for testing, all of which takes a week or so, depending on their current schedule. When the molder has the necessary materials, the mold will go into a molding machine for testing. This procedure is referred to as process validation, which establishes the optimal process parameters for a particular mold, so that it consistently produces parts that conform to the specifications. This can be a lengthy process to perform, so expect it to take at least a week.

The result of this step is the production of first article samples. Once the molder performs their quality inspections and the samples are conforming, they will provide them to you along with the inspection report. If the first articles are approved, the mold should be ready to go into production. However, if there are issues, the process may need to be manipulated, which could take a few days, or it could be something more serious, which might take longer to remedy.


Once a mold is placed into production, it usually is stored at the molder’s facility for quick and easy access when orders for parts are submitted. When a purchase order is received, a molder needs to verify terms, pricing and its inventory of raw material, finished goods and other associated items (e.g., packaging) and put the order on its production schedule. The time a molder takes to process and fill orders can vary, and most suppliers have stated policies, (which is good to get in writing). Nevertheless, production should begin for new orders within four weeks, unless there are unique circumstances.


While a molder can state their policy for the time it will take to start manufacturing parts after their receipt of an order, the duration of each production run, obviously, depends on the size of the order and on the cycle time for the mold. For example, an order for 10,000 pieces with a cycle time of 20 seconds will be done quicker than an order for 100,000 pieces with a 30 second cycle.

Prior to production, the mold needs to be retrieved from storage and placed into the machine, the machine needs to be cleaned from the last production run, the new material needs to be put into the machine, and the process identified during the process validation phase must be established. (There are more steps involved, but we’re just mentioning the main ones.) During and after production, quality inspections take place. If any secondary operations (e.g., machining, decoration, assembly) are needed, those are performed at the appropriate times and inspections should be performed afterwards. Once everything is completed, parts will be packaged, placed on pallets, and shipped from the supplier. Due to the number of variables here, giving an estimate of time would be difficult.


If tooling already exists and is being moved to a new supplier, the timing analysis basically will start with the Process Validation stage, although the mold inspection performed might be a little more in depth. The actual time involved with transferring molds can be fairly short, especially with a little upfront planning. Additionally, offering to buy any existing material from the incumbent molder creates some good will with them, because they literally won’t be left holding the bag, if they had to purchase specialty material to make your parts and they have some left in inventory. This saves time in that they may not drag their feet as much to get your mold ready to ship, and it gives the new molder the exact material they need to make parts, which should save some time, too.


Mold building and plastic injection molding are complex undertakings. Accordingly, professional suppliers will require a significant amount of data to perform their responsibilities properly, and it often takes a sizable amount of time to analyze and understand the applicable information, to collaborate with the customer and all relevant third parties, to obtain the necessary materials, to manufacture the item in question, to test and inspect it, and then to ship it to its destination.

Furthermore, every molding and manufacturing project is unique and, as such, the total time they take will vary, as will the duration of each constituent step. Nonetheless, having at least a basic understanding of the approach, chronology and processes should establish reasonable expectations of the timeframe required for each, and we hope this article has aided in that way.

If you have any questions we can answer, please do not hesitate to contact us.


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