LSR Injection Molding vs. High Consistency Rubber: Which is the Better Choice for Your Silicone Products?

When developing a silicone product, the choice between Liquid Silicone Rubber (LSR) Injection Molding and High Consistency Rubber (HCR) processing is one of the most critical decisions you'll make. It impacts everything from cost and production speed to part complexity and final performance.

LSR and HCR are both silicone elastomers with similar end-use properties, but their processing characteristics are vastly different. Understanding these differences is key to optimizing your manufacturing strategy.

Custom Medical Silicone Parts Manufacturer

The Core Difference: Viscosity and Process

Feature	Liquid Silicone Rubber (LSR)	High Consistency Rubber (HCR)
Consistency	Low Viscosity (Syrup/Liquid)	High Viscosity (Gum/Putty-like)
Molding Process	Fully Automated Liquid Injection Molding (LIM)	Compression or Transfer Molding (often manual)
Material Curing	Two-part, Platinum-Cured (Addition Cure)	One-part, typically Peroxide or Platinum Cured
Post-Cure Req.	Generally Not Required (Clean byproducts)	Often Required to remove volatile byproducts (Peroxide Cure)

📈 Comparing Cost and Volume

The true cost-effectiveness of each method depends entirely on your project's volume and part complexity:

1. Liquid Silicone Rubber (LSR)

LSR is the undisputed choice for high-volume, high-precision projects.

Pro: Automation & Speed: The automated closed-loop system requires minimal labor and boasts short cycle times (measured in seconds). This drastically reduces long-term labor costs.

Pro: Precision: Its low viscosity allows the liquid material to fill highly intricate, complex, and micro-geometry molds, leading to parts with tight tolerances and minimal flash.

Con: Upfront Investment: Tooling and specialized machinery are significantly more expensive than HCR, making it costly for small batches or prototyping.

2. High Consistency Rubber (HCR)

HCR (also known as Solid Silicone Rubber) is often favored for robust parts and smaller runs.

Pro: Low Initial Cost: The molding equipment (compression/transfer press) and basic tooling are typically less expensive than the high-precision LSR setup.

Pro: Material Properties: HCR, due to its high molecular weight, can sometimes offer superior tear strength and mechanical toughness in certain formulations.

Con: Labor & Waste: The process is typically labor-intensive, requiring manual loading of material pre-forms and post-molding trimming to remove flash, increasing labor costs and material waste per part.

Con: Cycle Time: Curing times are often longer than LSR.

🎯 Which Should You Choose?

Scenario	Recommendation	Rationale
High Volume / Mass Production	LSR Injection Molding	Automation, rapid cycle times, and minimal labor deliver the lowest cost per piece.
Medical / Baby Care	LSR Injection Molding	Platinum curing provides high purity, biocompatibility, and consistent output required for critical applications.
Complex Geometries	LSR Injection Molding	Low viscosity ensures the material easily fills detailed, thin-walled, or intricate cavities.
Low Volume / Prototyping	HCR Compression Molding	Lower upfront tooling and equipment costs make initial R&D and small production runs feasible.
Large, Simple Parts	HCR Compression Molding	The robust nature of HCR molding is well-suited for large gaskets, seals, and non-intricate industrial components.