Plastic injection family mould

Produce multiple complementary parts in a single injection cycle

One family mould integrates several footprint"footprints different in a single mould, allowing all the complementary parts of an assembly to be produced in a single injection cycle: cover + base, upper shell + lower shell, keyboard key set, stopper kit of several sizes. This approach, well thought out from the design stage, allows for reduce total tooling investment and to ensure the homogeneity of the parts (same material, same batch, same cycle).

Hybster supports you in the design of balanced family moulds, where each cavity fills correctly despite different geometries and volumes. Advanced rheological expertise is necessary to successfully achieve this type of tooling.

What is a family mould?

Not to be confused with a Multi-cavity mould who produces several pieces identical In a cycle, the family mould produces several parts different but complementary. Typical configurations:

• 2-piece assembly : hood + base of a casing, top + bottom of a shell, inside + outside of packaging.
• Multi-component kit Set of 4-6 pieces of the same product (buttons, hinge, gasket, screw covers).
• Size range plugs of several diameters, screwed onto the same material axis.
• Left/right parts : for symmetrical products (handles, fins, brackets).

Advantages of the family mould

• Reduced investment : just one mould instead of 2 to 6, representing a saving of 30 to 50% on total tooling costs.
• Perfect homogeneity between the parts of the assembly: same batch, same material, same manufacturing conditions.
• Simplified Logistics 1 order, 1 delivery, 1 stock management per cycle.
• Faster time to market : we start production with all parts simultaneously.
• Ideal for small and medium runs We do not pay a mould by reference.

Limits and precautions

• Difficult balance If the volumes of the parts are very different (ratio > 3:1), a mould can over-inject or under-inject. Solution: precise sizing of the feed channels.
• Fixed production ratio We always produce the same proportions of each reference. Difficult to use if one part wears out or is ordered more often than the others.
• Single material All prints use the same material. For parts requiring different materials, plan for separate moulds.
• Average dimensional accuracy Perfectly balancing multiple different impressions is complex. For very tight tolerances, a single-cavity mould is more precise.

If all your parts need to be strictly identical in very large quantities, opt instead for a Multi-cavity mould. If you have parts with different materials or colours, separate them into multiple moulds or use the bi-injection.

Typical use cases

• Electronic enclosures bonnet + base unit together.
• Cosmetic packaging Pot + cork + cap.
• Connection Enclosure + cover + fixing clip.
• Tools handle + tips + accessories for the same tool.
• Toys and consumer products Set of parts of the same set.
• Industrial equipment assembly elements of a modular product.

Our method for successfully creating a family mould

1. Analysis of parts and feasibility

Before designing a family mould, we verify the consistency of the parts: Single material, comparable thicknesses (ratio < 2:1 ideal), similar volumes (ratio < 3:1), same surface quality, same mechanical constraints. If the parts are too different, we recommend separate moulds.

2. Rheological balancing simulation

Critical stage: simulation Moldflow allows for the balanced simultaneous filling of different impressions by precisely dimensioning the feed channels (lengths, cross-sections). Without this step, a family mould almost always fails.

3. Design and manufacture

The mould is designed with a carcase compact integration of all imprints. The injection points are strategically positioned, sometimes at hot channels for finer balancing. Manufactured by our partners in 8 to 14 weeks depending on complexity.

4. Development and validation

Developing a family mould is more complex than a single mould: the conformity of each cavity must be validated simultaneously. Several days of testing may be needed to optimise the global parameters.

Indicative costs and timescales

• Family mould 2 simple impressions £12,000 to £25,000, 8 to 12 weeks.
• Family mould 3-4 cavities €20,000 to €45,000, 10 to 14 weeks.
• Family mould 5-8 impressions with movements €35,000 to €70,000, 12 to 18 weeks.
• Typical economy vs. split moulds : 30 to 50% of the total investment.

To go further

• For large series of identical parts: Multi-cavity mould.
• For small batches: Small-batch plastic injection mould.
• Optimise the cadence: hot runner mould.
• Full offer: Hybster plastic injection moulds.