How much does it cost · extrusion blow molding
In extrusion blow molding, an extruded plastic tube, the parison, is pinched in the mold and then inflated: according to Boothroyd Dewhurst, 10 to 50% of that parison becomes scrap depending on part geometry, so the material you pay for weighs more than the bottle or can (source: Boothroyd Dewhurst (DFMA), March 2026). The cycle runs from 10 s for a small, thin-walled part to 60 s and more for a large, thick-walled part, on a machine costed at $40 to $80 per hour (source: Boothroyd Dewhurst (DFMA), March 2026). Trimming costs $0.10 to $0.50 per part by hand and $0.05 to $0.15 on an automated trim press, and each punched hole $0.02 to $0.10 (source: Boothroyd Dewhurst (DFMA), March 2026). RFQdecoder counts these items one by one, converts them into euros at the ECB rate of the day and leaves the mold under tooling.
The process starts with polymer pellets, melted in an extruder and formed into a hollow tube, the parison. The tube is positioned between the two mold halves; as the mold closes, it pinches off the bottom of the parison, then pressurized air inflates it against the mold cavity to form the part (source: Boothroyd Dewhurst (DFMA), March 2026). Kautex, a blow molding machine builder, states that the process produces hollow bodies in series in all sizes, from a few milliliters to several thousand liters (source: Kautex, September 2025).
Pinch-off always leaves excess material at the top and bottom of the hollow part, flash that has to be trimmed (source: Plastics Technology, December 2012). According to Boothroyd Dewhurst, 10 to 50% of the parison ends up as scrap, depending on part geometry: the pinch-off length, flash line and sprue material all become trim waste, and the higher the scrap rate, the higher the material cost per part (source: Boothroyd Dewhurst (DFMA), March 2026). The material to pay for is therefore not the part weight but the parison weight, which includes the part, the flash and the pinch-off scrap (source: Boothroyd Dewhurst (DFMA), March 2026).
In practice this scrap is often recovered: trimmed, ground and fed back to the extruder (source: Plastics Technology, December 2012), it is mixed back with virgin material (source: MJS Packaging, May 2023). RFQdecoder nevertheless counts it as lost: a conservative approximation, stated on the quote.
The cycle runs from 10 s for a small, thin-walled part to 60 s and more for a large part with thick walls that needs extended cooling (source: Boothroyd Dewhurst (DFMA), March 2026). The typical range is 10 to 60 s, driven by extrusion rate, cooling and dwell time (source: Boothroyd Dewhurst (DFMA), March 2026). Thicker walls need more material and longer cooling in the mold; thin walls allow the fastest cycles and the lowest material cost (source: Boothroyd Dewhurst (DFMA), March 2026).
Flash also weighs on the cycle. Formed at the pinch points, it is typically twice as thick as the part’s maximum wall, and it at least doubles the time needed to fully cool the molding (source: Plastics Technology, June 2010). On a 1-gallon (about 3.8 liter) bottle weighing 63 g, a pinch-off insert cooled as a separate zone and machined with a trapezoidal cross-section cut cooling time by 4 s: the cycle went from 13 to 9 s, 31% less (source: Plastics Technology, June 2010).
The typical hourly rate for extrusion blow molding equipment is $40 to $80, against $80 to $150 for injection blow molding (source: Boothroyd Dewhurst (DFMA), March 2026). The machine cost of a part is this rate multiplied by the cycle time: at $60 per hour, a 35 s cycle costs 60 × 35 / 3,600 = $0.58.
Machine builders work to shorten this time per part. For 20-liter canisters, Bekum quotes high-speed production of up to 240 units per hour, with external cooling significantly shortening cooling times, and up to 2 x 12 articles per cycle on a double-station machine (source: Bekum, October 2026).
The tool costs the part item by item, using the values published by Boothroyd Dewhurst:
Amounts published in dollars are converted into euros at the ECB reference rate of the day: on 2 October 2026, €1 was worth $1.1225 (source: ECB, October 2026).
Two approximations are written on the quote. When no part size is given, the tool uses the typical cycle of 35 s, the midpoint of the 10 to 60 s range (source: Boothroyd Dewhurst (DFMA), March 2026). Scrap is counted as lost, although in practice it is often reground: the material price is therefore conservative. The mold is not part of the part price: it is declared separately, under tooling.
Assumptions (chosen for illustration, not taken from a source): 70 g HDPE bottle, with a geometry that sends 30% of the parison to scrap, one punched hole, trimming on an automated press, no size given; two batches, 100 parts then 10,000 parts. For each value published as a range, the example takes the midpoint. Mold setup and inspection are valued here at the machine rate used.
Published values used: HDPE at $1.00 to $1.50 per pound in Q1 2026, machine at $40 to $80 per hour, trim press at $0.05 to $0.15 per part, hole punching at $0.02 to $0.10 per hole, typical cycle of 10 to 60 s (source: Boothroyd Dewhurst (DFMA), March 2026); €1 = $1.1225 on 2 October 2026 (source: ECB, October 2026). In a real calculation, the tool takes the pellet price from the site’s material table.
Weight of the approximations. If the 30 g of scrap were fully reground and reused, the material to pay for would drop to 70 g, i.e. 0.1543 lb × 1.25 = $0.1929, $0.0827 less per part: that is the safety margin of the “scrap lost” assumption. If the size were given and the bottle counted as a small, thin-walled part, at a 10 s cycle, the machine would cost 60 × 10 / 3,600 = $0.1667 instead of $0.5833. At the ends of the published rate, the machine item at 35 s ranges from $0.3889 ($40 per hour) to $0.7778 ($80 per hour).
The price adds up parison material, machine time, trimming, punched holes, mold setup and inspection. Boothroyd Dewhurst publishes a typical cycle of 10 to 60 s on a machine at $40 to $80 per hour, $0.05 to $0.50 of trimming per part and $0.02 to $0.10 per hole. In the example on this page, with assumptions chosen for illustration, a 70 g HDPE bottle comes to €1.25 per part for 100 parts and €0.98 for 10,000 parts, mold not included.
According to Boothroyd Dewhurst, 10 to 50% of the parison, depending on part geometry: the pinch-off length, flash line and sprue material become scrap. In practice this scrap is often ground and mixed back with virgin material. RFQdecoder counts it as lost, a conservative approximation stated on the quote.
From 10 s for a small, thin-walled part to 60 s and more for a large, thick-walled part, according to Boothroyd Dewhurst, with 10 to 60 s as the typical range. When no part size is given, RFQdecoder uses 35 s, the midpoint of that range, and says so on the quote.
No. In RFQdecoder, the mold is declared separately, under tooling. Boothroyd Dewhurst puts an extrusion blow mold at $3,000 to $30,000, with a typical life of 1 million parts per cavity.
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