Plastics Injection Molding 101: Part 2
Plastics Injection Molding 101: Creating a Timeline and Budgeting
This blog series is for inventors and new businesses looking at creating a new product using the process of plastics injection molding. It’s aimed at anyone with limited experience in launching a new injection molded product.
Here we go Part 2: Creating a Timeline and Budgeting
The process of creating a new product can be a very time consuming and costly process. Here we will cover 3 basic aspects of launching a new product addressing an anticipated timeline and budget for each:
DESIGN AND PROTOTYPING -
The initial phase of creating a 3D design will mean employing an Industrial Designer who can turn your idea into a 3D rendering that can be passed along to a toolmaker for mold design. At this time you may also look to take advantage of 3D printing technology to get a proof of concept.
- Contract an Industrial Designer to create 3D files of your part. Ensure these files are in a .stp, .igs, or SolidWorks part file format.
- Make a prototype to obtain proof of concept and ensure the utility of your design.
Industrial Design rates run from approx. $85/hr to $125/hr. Most designers need at least 2 weeks to turn around a design with the number of hours required varying greatly according to the project and the number of revisions after an initial design. Expect that your designer will need a few business days to quote your design work and to pay at least a 50% deposit to get started. The balance will be due before you will obtain your design files. Please note that you should obtain transferable files upon payment in full. These are files with your design that can be revised by another designer if necessary and of which you have full rights to the design.
Prototyping generally takes two forms: 3D printing or short-run injection mold prototyping. Accurate can both 3D print and create short-run tooling. 3D printing is a great medium for prototyping runs of 1-10 parts generally. For prototyping runs of 50-100 or more parts, short-run injection molding tends to be more cost effective. 3D prints can have a turnaround time as little as 1-2 business days. Short-run molds tend to have a lead time of 2-3 weeks minimum. The advantages of a short-run injection mold are that it can be used for initial production and as well will offer much larger quantities of parts at a lower rate than 3D printing.
In summary ensure you have a few thousand dollars set aside for design and prototyping. In addition expect a timeline minimum of 2-3 weeks plus revisions.
MOLD MAKING -
With a 3D part design in hand along with a proof of concept prototype you are ready to quote a mold. The mold designer will need your 3D design files and will take those and may need to make some small adaptations to the part that will reap benefits when molded. The mold designer will need approval for these changes and you can verify the impact on your parts with your industrial designer before approving the changes requested.
Here is a list of what information your mold maker will need from you:
- Part drawings that include critical dimensions and tolerances for production
- 3D part files in .igs, .stp, or SolidWorks part file formats
- Desired plastic resin (your molder can help you make this choice)
- Desired finish
- Quantities you hope to sell per year
Accurate has an in-house tool shop and can quote your mold for tooling both in-house or made in China. Tooling quotes usually take 5 business days due to the complexity of quoting a new mold. We quote all large molds (for machines larger than 300 tons) using our Chinese supplier. All other molds are quoted in-house unless requested. Lead time on a mold varies greatly according to the current workload in the shop and the complexity of the mold. In general lead times are 4-12 weeks and include the 1-2 weeks it will take to sample your mold. Shop hours for mold makers are in the $80/hr - $125/hr range. Molds can take 30-80 hours to build, or longer.
There are 3 main factors that affect the price of a mold:
- The size of the part to be molded (larger parts mean larger heavier molds).
- The mechanisms that may be required to remove the part from the mold).
- The number of cavities in the mold (more cavities means a higher cost).
Terms usually include 50% due at the time of placing an order, 25% on mold completion, and 25% due upon approval of sample parts.
PRODUCTION AND SECONDARY OPERATIONS –
Parts production and secondary operations will be quoted in conjunction with your mold quote. Upon approval of sample parts from your mold, the molder will be able to fulfill your orders. The pricing of parts include: mold setup and take down, materials, labor, and machine hours. For example: Mold setup and take down might be $300, materials may be $.50/part, labor might be $20/hr, and machine hours might be $50/hr. If your part has a cycle time of 30 seconds and is a 2 cavity mold then you make 2 parts each 30 seconds. Thus over 10 hours you make 2400 parts. The cost per part for an operator assisted production run would be: $300 for setup + $200 for 10hrs of labor + $500 for 10 machine hours + $1200 for materials which is a total of $2200 or a per part price of $0.917. If your order was for 600 parts your per part price would rise as the setup fee would remain the same thus your per part price goes to $1.00 for a production time of 2.5 hours.
Some general rules for parts production are:
- When possible build a mold that is automated and does not require an operator.
- More cavities in a mold means a higher mold cost but lower per part costs.
- Large production runs and blanket orders make for lower per part prices as the setup fee does not impact the part price as much, and in addition machine hours and labor may be discounted.
Accurate can also offer some basic assembly and finishing services. As a custom molder we can do assembly, decorating, inserting, drilling, and other services. These services would be quoted on a per part basis upon request, usually at the same time as quoting the production of parts.
As a custom molder Accurate offers a wealth of experience in metal to plastic conversions as well as reengineering parts to eliminate gluing and other secondary operations. Accurate is experienced with over molding and the use of blowing agents for thicker walled parts. We would be happy to speak with you about the specifics of your project.
In summary, with a new product you will likely spend a few weeks and a few thousand dollars on design to start, a few thousand to tens of thousands for a mold that will take a month or more to build, then finally a few thousand dollars and a couple weeks for your first production run. Accurate recommend starting a new project at least one quarter before you plan to begin production.