A silicone mould for decorative stone tears at the corners after only a few dozen pours, and making a new one is costly and time-consuming. A cheap plastic matrix cracks from the first blow of a vibrating table. Batch production needs tooling that survives hundreds of cycles and releases the casting cleanly. Cast polyurethane delivers exactly that balance of wear resistance and elasticity. This article explains why polyurethane moulds outlast silicone in production runs, what is cast in them, and how to order tooling for your own design.
Why Polyurethane Suits Production Moulds
The primary reason is the combination of elasticity with high wear resistance and tear resistance. A mould must be sufficiently elastic for a casting with complex relief to release easily without damage, and at the same time strong enough to survive hundreds of pouring and stripping cycles. Cast polyurethane delivers both: it flexes, returns to shape, and resists abrasion and tearing simultaneously.
For a manufacturer this means lower per-unit cost. One polyurethane mould lasts far longer than a silicone one, so the tooling investment pays back across a production run of tile or stone. The smooth non-porous surface cleans easily from concrete residue and requires no complex maintenance, and moisture resistance ensures the mould does not degrade from contact with mix water. Mould manufacturing is among the factory services alongside standard product ranges.
What Is Cast in Polyurethane Moulds
Most commonly, polyurethane moulds are used for batch casting of concrete and gypsum products with complex texture. Artificial and decorative stone for facing facades and interior walls is cast in moulds that accurately reproduce the texture of natural stone. Paving slabs and kerbs, landscape decor elements, facade panels, and architectural details are all produced in polyurethane tooling.
The success of convincing texture depends on the material’s ability to capture the finest relief of the master sample and then reproduce it accurately cycle after cycle without distortion. The elasticity of polyurethane allows castings with deep relief and undercuts to be stripped without damaging either the mould or the casting. These applications cover construction, landscape design, and site furnishing, and related products are listed in the catalogue and by application sector.
Beyond building decor, polyurethane moulds are in demand wherever batch casting of parts with stable geometry is required. They are used for rubber-like and polymer components, tooling elements, and small-series parts of complex shape for which a metal press tool would be prohibitively expensive. The advantage of this approach is that a design change does not require retooling expensive machinery: a new mould is simply cast from the updated master sample. For small and medium manufacturers this is the difference between a flexible range and being locked into a few standard models.
Comparison: Polyurethane, Silicone, and Metal for Moulds
Direct comparison explains why polyurethane wins for production runs. Silicone renders the finest relief more accurately and handles higher temperatures; metal is rigid and dimensionally stable but heavy and cannot flex; polyurethane gives the service life and elasticity balance.
| Property | Polyurethane TIMOL | Silicone VMQ | Steel |
|---|---|---|---|
| Abrasion DIN 53516, mm³ | 38-39 | 150-350 | n/a |
| Tear resistance, kN/m | 40-120 | 5-30 | n/a |
| Tensile strength, MPa | 39-87 | 5-12 | 370-700 |
| Shore hardness | 85A-95A | 20A - 80A | n/a |
| Operating temperature, °C | -60…+100 | -60…+230 | -40…+500 |
| Rebound elasticity, % | 34-61 | 40-65 | n/a |
The key differences are in wear resistance and tear resistance. Silicone abrades 3-17 times more intensively than polyurethane (150-350 versus 38-39 mm³ by DIN 53516), and its tear resistance is only 5-30 kN/m versus 40-120 kN/m for polyurethane. This is precisely why a silicone mould tears at the corners during stripping first. Silicone wins only where the finest detail or high temperatures are required, and metal is suitable only for simple rigid matrices without undercuts.
How a Polyurethane Mould Is Made
The process begins with a master sample — an accurate copy of the future casting — which is fixed to a level base and enclosed with sides of the required height. The polyurethane compound is then prepared and poured so that it covers the entire relief evenly without air voids. After curing, the mould is disassembled, lifted from the master sample, and the texture transfer quality is checked.
The key to a good mould is care at every stage: a level base, tight side walls, correct surface preparation of the master sample before casting. Free-casting technology does not require expensive press tooling, so manufacturing a mould for an individual design is economically sound even for small production units. The factory produces tooling from the customer’s provided sample, drawing, or reference piece.
The quality of the entire production batch depends on the master sample, so it is prepared with particular care: surface defects are eliminated, because any flaw will be reproduced faithfully in every casting. The sharper and cleaner the reference piece, the more accurately the mould will capture the texture and the less finishing work the finished castings will need. If no ready sample exists, the mould can be cast from a drawing or digital model, and the factory selects the material and method for the required production volume and relief complexity.
Selecting Hardness and Mould Service Life
Mould material hardness is selected for the relief complexity. For castings with deep relief, undercuts, and thin projections, softer elastic polyurethane is used: it allows the casting to be stripped without breaking the casting or tearing the mould. For flat tile and simple geometric relief, harder material holds dimensions more accurately and gives clean edges. The hardness range of TIMOL polyurethane extends from 50 Shore A to 70 Shore D.
TIMOL engineer’s tip: mould service life depends most not on the material itself but on how well the hardness matches the relief. A mould that is too hard for a complex stone pattern will tear at sharp corners with every stripping cycle, while one that is too soft for large tile will produce castings with inaccurate geometry. Show the technologist the master sample or a photograph of the relief, and hardness will be selected to maximise the number of cycles.
Tooling That Pays Back on Production Runs
Polyurethane moulds outperform silicone precisely where service life matters: wear resistance is several times higher, tear resistance is 40-120 kN/m versus 5-30 kN/m, so the tooling survives more cycles and pays back in batch production of stone and tile. Free-casting technology allows a mould to be cast for your design from a sample or drawing, and the hardness range from 50 Shore A to 70 Shore D covers relief of any complexity. Technical material properties are described in the reference information section, and a mould calculation for your product can be obtained from a technologist via TIMOL factory contacts.