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The Manufacturing process · Raw Polymer → Finished Component

How Silton makes your component.

Every component we ship is compounded, tested, shaped and inspected at our own plants in Howrah. Scroll down the line.

01

Drawings. Samples. 3D Models.
Or Leave the Design to Us.

Send a drawing, a sample or a 3D CAD file (STEP, IGES, Parasolid, DXF or PDF). Or simply tell us what you need and leave the design to us. We study the application (temperature, media, ingress rating, closure force) and select the compound best suited to it.

Choosing the right compound is the single biggest factor in a long-lasting, failure-proof product. It is what lets a part outlast its maintenance schedule: Fit & Forget.

Drawing · Sample · 3D CAD (STEP · IGES · Parasolid) No Design? Leave It to Us Application Engineering Silicone · EPDM · FKM · NBR
PROCESS STUDY01 / 04
  1. Drawing, sample or requirement
  2. Check the application
  3. Compare suitable compounds
  4. Select the formulation
Ready to play

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02

Compound Mixing

The selected compound is mixed in a dispersion kneader under high pressure and controlled temperature, dosed to hit the target hardness, tensile strength and elongation, then finished on a two-roll mill into a homogeneous sheet.

Dispersion Kneader Two-Roll Mill Hardness · Tensile · Elongation
25 litre dispersion kneader with control panel at the Silton Rubber plant, Howrah 16 by 42 inch two-roll mixing mill
PROCESS STUDY01 / 04
Dispersion kneaderTwo-roll mill · side view
  1. Mix a batch in the kneader
  2. Transfer to the two-roll mill
  3. Add chemicals and form a band
  4. Take off the finished compound
Ready to play

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PROCESS STUDY01 / 04
  1. Test the compound
  2. Plot the cure response
  3. Verify specified properties
  4. Release the tested batch
Ready to play

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03

Compound Testing

No batch reaches production untested. A rheometer plots the cure curve of every mix; hardness, tensile strength, elongation, density and dispersion are verified against the specification before release.

Rheometer Shore A Hardness Tensile Strength Elongation at Break IS / BS / ASTM
FF moving die rheometer plotting the cure curve of a rubber batch Muffle furnace for ash and filler content testing Hot-air aging ovens for accelerated heat-ageing tests
04

Tooling

From your drawing, or reverse-engineered from your sample, the component is modelled in 3D CAD. Our CNC toolroom then machines the steel as per the manufacturing process best suited for your component.

3D CAD Model CNC Toolroom Reverse Engineering MS · EN31 · SS
PROCESS STUDY01 / 04
  1. Clamp the steel blank
  2. Lower the milling cutter
  3. Cut the cavity and clear chips
  4. Retract to reveal the tool
Ready to play

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CNC vertical machining centre cutting a steel mould under flood coolant in the Silton Rubber toolroom Freshly machined multi-cavity steel moulding die on the CNC bed at Silton Rubber
05 · Manufacturing

Two manufacturing routes

The component decides the die. Discrete geometries call for a moulding die, bolted into a hydraulic press. Components that can be extruded and finished downstream get an extrusion die, fitted to the extruder head.

Route ACompression mouldingIndividual moulded components Route BExtrusion & joiningContinuous profiles and joined seals
Lane A · 06

Compression Moulding

The moulding die from the toolroom is bolted into a hydraulic press. Compound blanks cure inside it under heat and pressure. The part is ejected, then flash trimmed.

PROCESS STUDY01 / 04
  1. Load the compound blank
  2. Close under heat and pressure
  3. Hold for curing
  4. Open and eject the part
Ready to play

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Lane B · 06

Extrusion & Joining

The extrusion die from the toolroom is fitted to the extruder head. The screw conveys compound through it. The shaped profile cures in a 70 ft hot-air vulcanizing oven. Cut lengths are joined end-to-end into jointless, endless gaskets.

PROCESS STUDY01 / 04
  1. Shape through the extrusion die
  2. Cure the continuous profile
  3. Cut to the required length
  4. Vulcanise the ends into a loop
Ready to play

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Extruder die head and the continuous vulcanizing curing line it feeds at Silton Rubber
07

Quality Control

Whether moulded or extruded, before dispatch all products go through dimensional inspection against IS, BS and ASTM standards and a visual check, followed by documented dispatch.

Dimensional QC IS / BS / ASTM Documented Dispatch
PROCESS STUDY01 / 04
  1. Position the component
  2. Measure against the drawing
  3. Verify dimensional requirements
  4. Approve for dispatch
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Packing & dispatch

PROCESS STUDY01 / 04
  1. Prepare the finished parts
  2. Pack the components
  3. Close and label the package
  4. Ready for dispatch
Ready to play

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All in-house. From compound to component.

Compounding & Mixing

Dispersion kneader plus chilled-roll mixing mills. Every formulation mixed in-house.

In-House Test Laboratory

Moving Die Rheometer, tensile, hardness and abrasion testers, aging ovens.

2 Automated Microwave CV Lines

Dedicated continuous vulcanization lines for EPDM and Silicone.

20+ Hydraulic Moulding Presses

From 10"×10" up to 43"×31" platens, including automatic presses.

Dispersion kneader compounding line at the Silton Rubber plant, HowrahMoving die rheometer in the Silton Rubber test laboratoryRubber extruder with heated barrel and die head at the Silton Rubber plant, Howrah

Ready when you are.

Send a drawing, sample or spec. Samples turned around extremely quickly.

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