There are two main components to molding a good part. The tooling and the process.
And while the process is important, tooling will hit you in the pocketbook right from the start. In fact, in some cases, the cost of tooling is a factor in choosing a molding process. Therefore, it will be important to know everything that goes into creating a tool so that you can better understand where your money is going.
Typically, tools used for reaction injection molding are much the same as those used in injection molding and are made from (in order of cost) Steel, Nickel Shell, Aluminum, Epoxy, or in some cases, Silicone. The decision to choose any one of these over another will depend on a number of factors including the temperature and pressure requirements of the process, the surface finish of the part and the number of parts needed.
Steel Tooling is the most expensive but also the strongest. Steel tooling is used any of the following instances: when high temp and pressure is required (SMC), when producing very large volumes (50,000+) or when a Class A high gloss surface finish is needed.
At Romeo RIM, we rarely use steel tooling as large RIM parts tend to be ordered in lower volumes. And since reaction injection molding works at much lower temperatures and pressures, the cost of steel doesn’t justify its use.
Temp & Pressure
Nickel Shell tooling is also very expensive, but much lighter than steel making it easier to work with, machine and ship. This type of tooling can also achieve an extremely high gloss finish.
Because Nickel Shell tooling is even lighter than Aluminum, we at Romeo RIM utilize nickel shell tools when the size of the parts begin to push the upper limits of our size capacity. We also use them to achieve a very high gloss surface finish (70-80 on a 60 degree scale).
Temp & Pressure
Aluminum tooling is a popular option because it still performs relatively well at higher temperatures and pressures. And with the advancement in aluminum technologies over the years, there is a decreasing need to use steel tooling in even higher volumes.
Different grades of aluminum also allow for flexibility in getting the most bang for your buck.
Q10 – is considered the best quality forged aluminum. It can provide high gloss finishes and be used in higher volume production runs.
M1 – The most popular cast aluminum grade used for most projects as it balances quality with cost.
M5 – A cost effective cast aluminum grade that can be used when you need a grain surface finish and production runs in lower volumes.
At Romeo RIM, we utilize Aluminum tooling almost exclusively. This is because Reaction Injection Molding (RIM) doesn’t require high temperature and pressure. Our engineers learn to understand your project and can match you with the right grade aluminum to help maximize your ROI.
Temp & Pressure
Composite or epoxy tools are limited to short, prototype runs only as these tools generally don’t last much longer than 100 shots. The options for a desired surface finish is also very limited.
We use Epoxy tooling only for prototyping.
Temp & Pressure
The lead times for all tool materials will vary. Heavier, denser steel is much more difficult to machine than, say, aluminum which, of course, effects the lead time. Below is a list of tooling types with an approximated lead time.
Epoxy – 6 weeks
Aluminum – 12-16 weeks
Steel – 16-20 weeks
Nickel Shell – 24 weeks
To give you some more insight into what goes in to making a tool, here are the lead times broken down by each step of the mold making process.
Mold design (1-2 weeks)
Designing the mold is the first step where our engineers will take the CAD model of your part and design a mold to produce it accurately and efficiently.
Order aluminum block and sent to Tooling shop (1 week)
The correct size aluminum block needs to be ordered and shipped to the tooling shop
Machine it (2-3 weeks)
The tooling shop will receive the block, place it in their order queue and begin the process of machining the core and the cavity. Depending on the size of the mold, this can take weeks to get the details to spec.
Gun drill cooling lines (1-2 weeks)
One step that is often overlooked is the drilling of cooling lines. This is a very precise process that allows lines to be inserted into the mold for cooling via water/oil.
Final assembly (2-3 weeks)
The tool will then be assembled with guides, spotting (to ensure the mold closes properly), mounting brackets and cooling lines.
Surface prep (1-2 weeks)
After the tool is assembled, the final surface finish is applied, either by a bead blast for a grainy finish or highly polished for a glossy finish
Sent to RIM molder (1-2 weeks)
It’s finally sent to the RIM molder where it will be mounted and ready for first shots.
We mentioned above that the two main components to molding a good part are the tooling and the process. When your tool gets shipped to your RIM molder, it is up to them to have the right manufacturing process in place to ship a quality part.
If you are familiar with injection molding, you may have heard about a mold flow analysis. This is a computer model that simulates the flow of the material into the mold. With this type of analysis, you can accurately predict the flow to achieve a quality part within the first few shots, if not the first.
Unfortunately, the reaction injection molding process does not have any such predictive tools. And because of that, it will be very important to choose a RIM Manufacture with good standards and procedures to get the best parts possible.
THE ROMEO RIM WAY
With over 35 years of experience manufacturing reaction injection molded parts, we are EXPERTS in understanding how our material will react within the mold so that you get a good, quality part every time.
Our manufacturing philosophy starts with Lean practices which helps to eliminate waste, either from wasted movements or actual material waste.
We have instilled 5S practices as well to help keep all employees aligned, from management to machine operator.
We utilize cross functional reviews from product engineering to manufacturing engineering to operations…we discuss moldability, manufacturability, shipping and handling.
Romeo RIM’s Reaction Injection Molding. For Bigger, Stronger, Lighter™ parts.