LSR Injection Molding Cost & Energy: How to Calculate Cost Per Part (2026)

LSR injection molding cost per part is driven mainly by material, cycle time, and energy. This guide breaks down each cost element, shows a sample per-part calculation, and explains how servo drives and cold runners reduce energy and scrap for lower 2026 production costs—useful for engineers and buyers comparing quotes.

What are the main cost components of LSR injection molding?

LSR part cost is the sum of five elements: material, machine (energy + depreciation), labor, mold amortization, and overhead/scrap. Material and cycle-time-linked machine cost usually dominate. The shares below are typical; high-precision medical work shifts more weight to material and scrap control.

How do you calculate LSR cost per part?

Cost per part = material cost + (machine rate x cycle time / cavities) + labor + mold amortization + overhead. The key lever is cycle time divided by the number of cavities, because it spreads machine and labor cost across more parts.

Worked example (illustrative)

Assume a 4-cavity tool, 30-second cycle, and 2 g of medical-grade LSR per part. Per shot the machine produces 4 parts, so the effective machine time is 7.5 seconds per part. If the loaded machine rate is, say, a fixed hourly figure, you divide it by parts-per-hour to get machine cost per part, then add material and a share of mold and overhead. Lowering the cycle to 24 seconds or moving to an 8-cavity tool can cut machine-and-labor cost per part by 25-50%.

• Material per part: part weight + runner share (cold runner ≈ zero runner waste) x material price per kg.
• Machine per part: hourly machine rate / (3600 / cycle-seconds x cavities).
• Mold per part: tool cost / planned lifetime part quantity.

How much energy does an LSR machine use?

Energy use depends on drive type and heating: servo and all-electric machines typically use 20-50% less energy than older hydraulic units. LSR also benefits from mold heating (curing) rather than cooling, so thermal management and insulation matter. Two factors dominate machine energy: the drive (motor + pump) and the mold-heating circuit.

How does cycle time affect cost?

Cycle time is the single biggest controllable cost driver after material. Shorter cycles spread fixed machine and labor cost over more parts. Cure time scales with the thickest wall section, so design and process tuning both matter.

• Reduce wall thickness where the design allows—thick sections lengthen cure time disproportionately.
• Optimize mold temperature and injection profile to cure fully without over-curing.
• Add cavities (where part size and tonnage permit) to multiply output per cycle.

How can you reduce LSR production cost?

The biggest savings come from servo drives, cold runners, multi-cavity tooling, automation, and energy monitoring. Each attacks a different cost element, and together they compound.

• Servo / all-electric drive: cuts energy 20-50% and tightens repeatability, reducing scrap.
• Cold runner system: eliminates runner waste—significant when material is 40-60% of cost—and reduces trimming labor.
• Multi-cavity tooling: divides machine and labor time across more parts per cycle.
• Automated part removal: lowers labor and improves consistency on high-volume runs.
• Energy monitoring / MES: tracks kWh per part and flags drift before it becomes scrap.

Conclusion

To control LSR injection molding cost, measure each element—material, energy, cycle time, labor, tooling, and scrap—then attack the largest. Material and cycle time usually offer the biggest wins, and equipment choices such as servo drives, cold runners, and multi-cavity automation lower both energy and waste. TYM designs energy-efficient LSR machines and turnkey lines that help manufacturers cut cost per part while holding quality. Contact us for a production cost or equipment-selection assessment.

FAQs

Q:How much does it cost to mold an LSR part?

There is no single figure—cost per part depends on material grade, part weight, cycle time, cavity count, and automation. Material typically accounts for 40-60% of the total. The most reliable approach is to calculate each element and divide machine and labor time by parts-per-cycle.

Q:How much energy does an LSR injection machine consume?

It varies with size, drive type, and mold heating. Servo and all-electric machines generally use 20-50% less energy than older fixed-pump hydraulic units because power is drawn only during motion. Mold-heating circuits are the other major load, so insulation and temperature control matter.

Q:Does a cold runner reduce cost?

Yes, significantly. A cold runner delivers material straight to the cavity with little or no runner waste. Because LSR material can be 40-60% of total part cost, eliminating runner scrap and the labor to trim it can noticeably lower cost per part over a production run.

Q:How does multi-cavity tooling affect cost?

Multi-cavity tooling raises tool cost but lowers cost per part by producing more parts each cycle, spreading machine and labor time across them. The break-even depends on volume: higher annual quantities justify more cavities, while low-volume parts may favor simpler tools.