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the difficulties lie in plastic mold valuation
By AriMarch 2nd, 202660 views
1. Core Difficulty: Molds are Non-Standard Custom Products
This is the most fundamental challenge. Unlike buying a television, every mold is a "one-time development project."
Uncertainty in the Manufacturing Process: Molds are "trialed" into existence. Before the trial run, no one can guarantee 100% that the mold will succeed on the first attempt. The costs for later modifications, welding, and adjustments are very difficult to estimate accurately during the quotation phase.
Lifespan Requirements: A mold designed for 100,000 shots versus one designed for 1,000,000 shots has vastly different heat treatment processes, steel selections, and structural designs, leading to enormous cost differences. However, these differences may be completely invisible from the outside.
2. Technical Difficulty: Hidden Structures and Design Variables
Quotations usually rely only on the product drawing, without a detailed mold structure diagram.
Undercut Treatment: For a small snap-fit on the product, should a "slider" or a "lifter" be used? Should an "oil cylinder" or a "spring-loaded core" be used? The cost difference between different structures can be several times. The estimator must rely on experience to guess the most reasonable structure.
Gate Location: Where is the injection point? Will it be a pin-point gate, a submarine gate, or a hot runner? This determines the complexity of the mold.
Tolerance and Shrinkage: A tolerance of ±0.01mm on the drawing might necessitate slow wire EDM and precision spark erosion, causing machining time to increase exponentially. Conversely, if it's merely a cosmetic part requiring a "textured surface," it might involve additional texturing costs and higher demolding angle requirements.
Trial Run Costs: How many trial runs will be needed? What are the material costs, injection molding machine hourly rates, and labor costs for each trial? High trial run success rates mean lower costs; if the mold design has flaws requiring repeated modifications, costs can spiral out of control.
Communication and Design Change Costs: Clients often modify product designs during development, leading to mold rework. These communication costs and the time spent on repeated confirmations are hard to factor into the initial quotation.
4. Market Difficulty: Competition and Information Asymmetry
Different Technical Solutions: For the same product, Factory A might design a 1+2 cavity mold, while Factory B designs a 1+4 cavity mold. Although Factory B's mold has a higher unit price, the cost per part is lower. Clients often only look at the total mold price, causing Factory A, which adopted a more conservative technical solution, to lose the order due to a higher quoted price.
Regional Differences: Quotation systems vary significantly between the Pearl River Delta, the Yangtze River Delta, and inland areas. The cost structure for the same mold is completely different across different regions.
Summary and Recommendations
For fast and accurate plastic mold valuation, a single method is often insufficient. A more reliable combination strategy is:
Screening Phase: Use the insert weight method or mold base estimation method to provide a rough price range within 10 minutes, determining whether the project is worth pursuing.
Detailed Quotation Phase: Combine the feature analogy method (checking historical data) with the structure breakdown method (roughly calculating specific man-hours for CNC, EDM, wire cutting) to issue a formal quotation.
Establish Risk Clauses: Include a note in the quotation or contract stating, "The quotation is based on current product data. If subsequent product design changes lead to modifications in the mold structure, the price will be subject to renegotiation." This serves as a final line of defense against quotation inaccuracies.
