Moldmaking and Prototyping: Here’s How to Find the Right Moldmaking Compound
From chocolates to theater makeup, from gears to concrete wall coverings: with moldmaking and prototyping, just about anything is possible – provided you have the right silicone moldmaking compound. We’ve compiled eight questions here that will help you find the perfect ELASTOSIL® M product for your project.
You can also download our interactive brochure (PDF), where you will find a summary of the following content as well as an interactive, quick selection guide.
In order to use the full functionality, please download the brochure and open it in Acrobat (Reader or the full version).
1. How Faithful Do the Dimensions of the Replica Need to Be?
Addition-curing ELASTOSIL® M products offer maximum reproduction and dimensional accuracy for manufacturing molds used in tire production.
ELASTOSIL® M is available as addition-curing and condensation-curing products. Both offer unique advantages and disadvantages, the primary difference being the degree of shrinkage during curing.
Do you want your replicas to be as accurate as possible?
Addition-curing ELASTOSIL® M products do not shrink during curing, lending them 100% dimensional accuracy. They also cure quickly and can be used as soon as they are released from the mold. However, it's important to consider the substances used in the process, as these can disrupt curing.
Condensation-curing ELASTOSIL® M grades open the door to almost unlimited creativity.
Are you looking for perfectly replicated details at an affordable cost?
Condensation-curing ELASTOSIL® M products are generally less expensive, but they shrink between 0.4% and 0.8% during curing. This has no impact on the accuracy of the details, however. Inhibition is not a risk, and the compound cures reliably at room temperature and at 40% humidity.
Go to products2. What Material Should You Use for Molding?
Molds made of silicone rubber are compatible with many different materials. Casts made of plaster, ceramic, wax or concrete pose no problems and can be produced in large quantities. Casting resins, however, can degrade the mold over time, so if you plan to make a large number of casts, you should choose resin-resistant ELASTOSIL® M grades.
3. How Quickly Does the Mold Need to Be Ready?
The ELASTOSIL® M product range includes normal and fast grades, with curing times ranging between 3 and 24 hours. The curing time refers to the number of hours that need to elapse before demolding.
Another important factor is the pot life, which describes how long a silicone rubber compound can be worked once it has been mixed. Pot life for ELASTOSIL® M grades ranges from approximately 7 to 90 minutes.
With addition-curing grades, both of these parameters can be controlled with additives and heat. In the case of condensation-curing grades, this is accomplished by choosing a suitable curing agent.
Our product overview lists the curing time and pot life for all ELASTOSIL® M grades.
4. Will You Be Working on Vertical Surfaces or Overhead?
Find out more about how you can adjust thixotropy to suit your processing needs.
You can choose between ELASTOSIL® M grades that can be poured, spread or kneaded, depending on your application. Spreadable grades do not run down walls and do not drip when applied overhead.
5. Is Good Flowability Important?
Pourable ELASTOSIL® M grades are available with varying viscosities and degrees of flowability. This can be important when mold production is automated and dosing and blending equipment is used.
The higher the viscosity, the thicker the material is. Viscosity ranges between 1 and 5 mPas for water, between 2,000 and 3,000 mPas for honey and typically between 1 and 2 million mPas for lard.
6. How Hard or Soft Does the Finished Mold Need to Be?
The hardness of cured silicone rubber is given in Shore A units. The ELASTOSIL® M portfolio includes soft, medium-hard and hard grades covering an overall Shore A range of 11 – 60. Selecting a softer grade is helpful for complex molds, as this makes demolding easier. Hard grades are suitable for very stable molds.
The higher the Shore A value, the harder the cured rubber. Shore A hardness is roughly 10 for gummy bears, approximately 65 for rubber bands and generally 95 for car tires.
7. Will the Mold Be Subject to Strong Forces?
To demold objects with pronounced undercuts, the mold often has to be stretched extensively, a situation calling for good tear resistance.
Tear resistance of standard ELASTOSIL® M grades ranges up to 10 N/mm. Specialty grades achieve 20 – 30 N/mm.
8. Are There Special Requirements?
To accommodate special demands, ELASTOSIL® M grades are available that are heat-resistant, transparent or suitable for food contact.
Transparent molds are helpful for delicately structured objects or for viscous casting materials, as these enable you to see whether the material has flowed into every corner of the mold. For rapid-prototyping applications, transparent molds allow manufacturers to position the mold parting line strategically for cutting out the product master.
Quick Selection Guide: Finding Your Bearings Is Just a Click Away
In addition to summarizing all of the information you need to choose a product, our interactive brochure also provides a quick selection guide. Just a few clicks will take you from the starting casting material to a recommendation for a suitable grade of ELASTOSIL® M.