Compression Molding of Silicone Materials: Pros and Cons

Many Inventors, Engineers and Project Managers believe that injection molding is the best solution for their molded silicone products. However, this is not always the case due to the many variables and constraints of manufacturing silicone parts.

First and foremost, anticipated volume is always a true concern. If you only need to mold 1 to 20,000 pieces then a compression mold is more than suitable. Secondly, do your parts have multiple undercuts or is the geometry highly complex? If so, then a compression mold may be the most viable option.

Compression Molding

During the prototyping phase, a compression tool allows for rapid turnaround time. At Albright Technologies, we will produce a compression mold manufactured out of aluminum, along with engineering samples in 15 business days or less. Now, let’s take a look at the pros and cons of compression molding.

Compression Molding

Pros:

  1. Parts are dimensionally to specification and made with specified materials
  2. Short set-up times, allowing materials and colors to be changed quickly
  3. Flexibility in mold design
  4. Tools with multiple cavities can be made with less concern of balancing
  5. Welding allows for tool modification
  6. Faster mold manufacturing turnaround time
  7. Parts with multiple undercuts can be manufactured
  8. Mold tool cost is lower than injection
  9. Cost of compression molding machines is low
  10. Reduced molding process development time (day(s) not weeks)

Cons:

  1. Slower part production rates
  2. Can be difficult to control flash

Due to the nature of our business as a silicone prototyper and low-volume production molder, compression molding is a great fit. It offers our customers a less expensive, yet rapid option (when compared to injection mold tooling) to turn their product designs into reality. We provide our customers with silicone parts that are molded from complex mold tools with many undercuts as required.

Now, it is time for some questions for discussion. Do you or your company utilize compression mold tools to manufacture silicone parts? How would you rate your overall experience with the compression molding process? How much of your molding business is processed utilizing compression molds?

When turning your design into a silicone prototype, select the World’s Premier Source for Silicone Molded Parts. Get your 3D Models quoted today, visit our RFQ page.

Get a Free Pass to MD&M West from Albright

Visit with Christi, Jeff and Ryan in sunny and beautiful Anaheim, California this February at the MD&M West Trade Show! The show is located at the Anaheim Convention Center at 800 West Katella Avenue in Anaheim and Albright has Booth 1083.

The Exhibits schedule is as follows:

Tuesday, February 10, 2015                         10 AM to 5 PM

Wednesday, February 11, 2015                   10 AM to 5 PM

Thursday, February 12, 2015                       10 AM to 4 PM

Albright will be exhibiting our silicone prototyping and production solutions to attendees in Booth 1083, located at the left rear of Expo Hall D.  We are currently offering free passes to our partners.  Save $95.00 dollars on registration, visit MDMwest.com/invite and use the source code, invite.

We look forward to seeing you in Sunny California next month. Stop by Booth 1083 for a visit and learn about the latest at Albright Technologies and the latest in the medical silicone industry!

MDMwest.com/invite

Selecting a Suitable Medical Silicone

Silicone materials can be compounded to create materials that are both, bio-inert and fully compatible with biological systems. Medical silicones are compounded in a similar manner as general purpose silicones to obtain certain characteristics, such as durometer, elongation and tear strength. However, medical silicones undergo additional processing to remove unwanted residuals. This allows for the purest silicones to be manufactured for use in medical devices.

Silicone manufacturers have created systems to determine which materials should be used for a variety of bio-contact applications. These suppliers have created in-house certifications that are based on the positive results of a series of USP (U.S. Pharmacopeial Convention) Tests. There are six separate USP tests, from Level I to Level VI. Materials that meet each of the six tests, are often referred to as “Grade 6″ materials.

To better understand the requirements of each USP test, please see the table below.

table 1

Silicone manufacturers have created several groups in which to place these various medical silicones based on their anticipated use.

  1. Food Grade Silicones: Silicones of this group must meet USP tests, as well as FDA and USDA guidelines and criteria. Materials from this group would commonly be found in food processing equipment in the form of seals or even spatula blades.
  2. Medical Non-Implantable: Silicones of this type do not see use inside the body. Typical applications include tubing and one-time use disposables.
  3. Medical Short Term Implantable: These particular silicones can be implanted into the body for up to 29 days. A few applications include catheters and surgical tools.
  4. Medical Long Term Implantable: Silicones from this group can be implanted for a period greater than 29 days. Typically these materials are used in cardiovascular implants and remain in the body until end of life.
  5. Pharmaceutical: Silicone materials used in the pharmaceutical space, must pass all six USP tests and must be compatible with any drug coming into contact with the part. Drug delivery devices, such as punctal plugs, are typical applications in this group.

Determining which medical grade silicone material is required is based on the function and use of the medical device to be manufactured. Albright’s staff of engineers can assist you in material selection so that your medical application’s requirements are met. Please remember that although many silicone suppliers have conducted USP bio-compatibility tests on their respective materials, all finished medical devices will still need further USP testing. To learn more about medical silicone materials visit our Silicone Material page.

A Guide to Shore Durometers

Before manufacturing silicone parts, it is important to select a finished durometer for the part or product that you will be molding. Depending on the requirements of the project, the silicone finished part may be near gel-like or very stiff. Durometer is a measure of hardness that is used in elastomers, polymers and rubbers. Hardness may have many definitions, but in our case with regards to Shore durometer, hardness is defined as a material’s resistance to indentation.

Durometer Test PictureThe Shore durometer scale was created by Albert F. Shore in the 1920’s. Originally, the result was just signified by a number, for example 50 durometer. As time progressed, multiple durometer scales were created. The Shore durometer scales that are most commonly used in plastics, rubber and silicone are the A, D and 00 shore scales.

There are two main differences amongst these scales. First, the configuration of the indenter that is pressed into the material is different with each scale. Second, the hardness range is different with each of the three scales. The Shore 00 Scale measures rubbers and gels that are ultra soft. The Shore A Scale measures rubbers that range from soft and flexible to hard with almost no flexibility. The Shore D Scale measures the hardness of hard rubbers and hard plastics.

Below is a table of common finished products and their respective durometers.
durometer_with_logo_small_580Here at Albright, we use the Shore A scale to quantify our molded silicone durometers. The Shore A scale ranges from 0 to 100. An example of a “0” durometer Shore A silicone molded part would be a very soft shoe insole. Near the opposite end of the scale, an example of an “80” durometer Shore A silicone molded part would be an o-ring seal or a stiff silicone kitchen spatula. Every day, Albright molds products in materials that range in finshed durometer from 10 to 80 on the Shore A Scale.

What materials and durometers have you molded parts in? What durometer Shore scale do your materials come in? How do you determine what durometer of material to use?

Please remember that the durometer selected will be based on the requirements of your project. If you need assistance determining a durometer for your next silicone project, Albright engineers and technical staff are here to help. In addition, we can provide samples of silicone in various Shore A durometers. Want samples of silicone durometers? Visit our free durometer sample page on the Albright web site.

Insulate LED Lighting with Silicone

LED lighting technology is increasing in usage by the day. Commercial LED applications require robust construction and must be visually appealing to potential customers. Silicone is used to insulate outdoor LED applications to protect them from corrosion and UV light damage. Optically clear grades of silicone can protect LED lights from the elements while maintaining aesthetics. Learn more here: http://bit.ly/1nCV8jf

Were you aware that silicone is used in LED lighting applications? Did you know that silicone can be used in LED lighting, among others substrates, to protect from the environment? Have you ever used silicone in your LED lighting products?

Electrolube's silicone resin protects LED lighting and preserves its aesthetics

The Next Era of Computing will come in the Form of Wearables

Silicone is being used as a material in wearables with computer sensors. The silicone is overmolded on to the computer sensors and then attaches to the skin like a band aid. Learn more here: http://nyti.ms/1wzdh0J

Now for some quick questions regarding wearables. Were you aware of the predominate usage of silicone in wearable applications? Silicone is great for overmolding applications, have you worked on any of these types of applications? If you have worked with silicone overmolding in the past, what advantages or disadvantages did you experience?

7 Reasons to Choose Albright for your Silicone Prototypes

1. Our standard turnaround is 15 business days.

2. Three, five and ten business day expedites are available when you need parts fast.

3. Injection, compression and transfer molding processes are available.

4. Albright designs and manufactures all tooling in-house for complete control.

5. We have an ISO Class 7 hard walled clean room for medical and biopharmaceutical devices.

6. We stock a massive inventory of silicones to accommodate any application.

7. Albright’s Quality Management System is ISO 13485:2003 certified by TÜV SÜD.

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How Albright’s Quality System Affects Your Non-Medical Part

The main benefit of Albright’s QMS for non-medical customers is the overall Quality System emphasis on improving compliance to repeated processes. The Quality System is especially important in the integrity of the silicone material Albright uses and in the consistent, high-tech quality inspection applied to finished parts.

Click her to read more.