Chapter 6: Benefits & Unique Properties of LSR


Throughout the past several decades, one of the most significant challenges for the auto industry has been finding a suitable material that can maintain its initial properties. Because a material that had high strength, durability and resistance in high-temperature environments — such as inside an engine compartment — was needed, the industry used to rely on metal which had those properties.

However, metal is a dense material that increased the fuel costs for cars and had an outcome of low control over the safety of passengers as well as drivers.

benefits properties lsr

New materials were modified to keep up with the extreme demand for higher power and performance in automobiles, but now LSR has replaced ethylene propylene diene monomer — EPDM — which is a kind of synthetic rubber. LSR can be found in automotive wire grommets made of rubber, battery seals, headlamps, gaskets, ignition cables, hoses, shock absorbers, spark plug boots and other auto components.

There are many advantages of implementing LSR mechanisms in the automotive industry as various auto silicone parts surpass the features of conventional plastic and rubber methods. LSR products manufactured by SIMTEC Silicone Parts not only are lightweight, which increases fuel efficiency, but the components also reduce emissions/air pollutants such as CO2 and NO2.

benefits properties lsr

With our innovative technology, we can design and manufacture high-volume molding, secure processing, provide consistent quality parts and improve productivity for any OEM or tier-one or tier-two company. To optimize the plethora of liquid silicone rubber advantages and benefits, the injection molding process must provide value and ease of use — and LSR injection molding machines do just that.

With the precise design of elaborate parts featuring unique colors, LSR components from SIMTEC are changing traditional rubber applications and are being used where traditional rubber is not often seen. With benefits ranging from high tensile and tear strength to elevated ozone, UV, oil and fuel resistance, liquid silicone rubber proves it is an ideal material for demanding auto industry properties. Other common advantages include good elongation, flexibility and hardness.

LSR offers properties that are otherwise not obtainable with traditional rubber materials because it’s an automated process that cures faster and can withstand extremely high and low temperatures. It results in a minimum waste generation, reduces friction and has shorter cycle times.

Whether you require rubber grommets for automotive purposes or need other rubber moldings for cars, liquid silicone rubber from SIMTEC can offer the following advantages:

  • Biocompatibility: Liquid silicone rubber has undergone extensive testing to make sure it’s compatible with human skin and fluids. Compared to other forms of elastomers, LSR from SIMTEC is resistant to bacteria growth and will not corrode or stain other materials. With odorless and hypoallergenic properties, our LSR auto parts comply with FDA requirements and can be sterilized.
  • Chemical resistance: LSR is resistant to oxidation, water and some chemical solutions like acids and alkali. Chemical resistance is especially pertinent in the auto industry because high-temperature silicone rubber grommets can experience radiation from the sun, salt from roads and other hazards from inside the engine compartment.
  • Cost-effective and elimination of excessive assembly parts: Because the 2-Shot injection molding process can manufacture and combine more than one part at once, it saves you money as opposed to paying for several procedures. Instead of using different materials for a variety of functions, SIMTEC’s technology integrates several into one component. Although the system is more comprises of multiple steps, it’s also more cost-effective and streamlined.
  • Durability: With the ability to uphold its properties under extreme temperature levels, parts made from LSR injection molding will not melt and are fire retardant. As opposed to pieces made from plastic injection methods, LSR is the ideal choice for components under the hood of vehicles and close to engines.
  • Electrical properties: The insulating properties of LSR technology are a perfect option for electrical applications. The parts can perform in higher and lower temps compared to conventional material, which protects electrical components from the environment.
  • Flexibility: Automotive wire grommets made of rubber maintain flexibility under dynamic loads, chemical agents and high temperatures that can be transported through cables, tubes or hoses. The objective of flexible liquid silicone is to reduce maintenance.
  • Thermal stability: Many OEM manufacturers, as well as tier-one and two auto suppliers, prefer the LSR injection molding process because it results in components that have thermal stability. As such, high-temperature grommets can withstand extreme temperatures — whether hot or cold — ranging from -58 degrees to 392 degrees F. Because it is heat resistant with a broad operating temperature range, LSR auto applications are ideal for under-the-hood components.

Other advantageous factors of LSR include:

  • Clarity
  • Compression resistance
  • Extended product life
  • Flexibility
  • Gas permeability
  • Low toxicity
  • Low viscosity
  • Resistant to tears and stress
  • Superior light transmittance

With the natural transparency of LSR, SIMTEC can produce custom, colorful and modeled products to fit your needs. It also saves energy, promotes economies of scale and has an Underwriters Laboratories (UL) component recognition. Having an UL Certification Mark means LSR is a tested and certified product according to UL, a global certification and safety consulting company. They investigate and verify that products are in accordance to model codes and regulations.

benefits properties lsr

The LSR market is promoting extensive research to develop the process of innovative technology even further. It will create more growth opportunities for the auto sector to continue making LSR applications such as LED headlights, gaskets and high-temp silicone grommets.


To determine the fatigue of LSR components, we calculate the mechanical response of LSR in the presence of dynamic loads. From here, SIMTEC experts can predict the lifetime of LSR products which will indicate when preventative maintenance is necessary. Fatigue tests also help to avoid an unexpected stoppage.

We analyze fatigue via two points of view. The first uses a variable amplitude of applied load where we try to stimulate real stresses that the product is subject to during service. The second relates to the nominal and constant pressure required to cause fatigue failure in a certain number of cycles.

Regarding liquid silicone rubber, an elastic strain of energy is partially transformed into different forms of energy when it deforms cyclically. It creates an increase in internal material temperature. Because of the higher viscoelastic behavior of LSR, the higher the dissipative process is involved and the higher the probability of cracking.

Fracturing can be aided by external factors like dirt and dust particles. And specific areas where cross-links occur can be different from the rest of the silicone material. Silicone rubber products often fail at cyclic stresses with values much lower than tear strength because of cumulative fatigue.

Therefore, SIMTEC designs to adhere to the following:

  • Create a safe design
  • Distribute dynamic stress evenly to avoid catastrophic failure
  • Pressures must be below the fatigue limit

We also use computer-aided engineering which can help us predict the performance of each LSR product during application.

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