Blow Molding Services — From Design to Finished Plastic Parts

Blow molding is the process of choice for hollow, one-piece plastic parts: bottles, containers, fuel and hydraulic tanks, air ducts, reservoirs, and structural housings. Compressed air inflates hot plastic against the mold wall, so the part comes out hollow without a core, a weld, or an assembly step.

If the part is hollow and enclosed, blow molding is almost always cheaper, because there is no core to pull and no need to mold two halves and join them. If the part is solid, has ribs, bosses, or precise mating features, use injection molding. Blow molding holds around 0.5 mm on molded dimensions where injection molding holds 0.05 mm, so precision features are the deciding factor.

Extrusion blow molding (EBM) extrudes a molten tube called a parison, clamps it in the mold, and inflates it. It handles large parts, handles, and complex shapes. Injection blow molding (IBM) first injection molds a preform on a core rod, then blows it, which gives better neck and dimensional accuracy on small bottles but cannot produce handles. Injection stretch blow molding (ISBM) adds an axial stretch to biaxially orient PET for clear, pressure-rated bottles.

Roughly 0.5 mm on molded dimensions, with wall thickness typically controlled to about ±3 to 5%, in line with GB/T 13510. Neck and finish dimensions on injection blow molded parts are tighter because the neck is injection molded rather than blown. Tighter tolerances are possible but cost cycle time and secondary operations, so we only apply them where the part needs them.

Through parison programming, which varies the extruded tube's thickness along its length so material lands where the part stretches most. Corners and deep draws thin out naturally, so we thicken the parison at those points instead of adding weight to the whole part. This is what keeps a tank light and still passing drop and burst tests.

Substantially less for the same part envelope. Blow molds are usually machined from aluminum with beryllium copper pinch-off inserts, they carry no core, no complex ejection system, and far lower clamp pressure, so both the material and the machining hours drop. This is why a large hollow part that would need a very expensive injection tool is often blow molded instead. Exact pricing depends on part size, cavity count, and finish.

Yes. Multi-layer co-extrusion blow molding builds the parison from several polymer streams at once. A typical automotive fuel tank uses an HDPE structure with an EVOH barrier layer at the centre to stop hydrocarbon permeation, plus a regrind layer to control material cost. The same approach works for chemical containers and packaging that needs an oxygen or moisture barrier.

PVC, PP, PE, and PET. HDPE is the most common choice for tanks and industrial containers because of its toughness and chemical resistance, PP suits hot-fill and higher-temperature parts, PVC gives clarity with good barrier performance, and PET is used with stretch blow molding for clear pressure-rated bottles. Food-contact, UV-stabilised, and medical-grade compounds are available.

Trimming and deflashing, drilling and punching, labeling and printing, and leak testing, followed by custom finishing and assembly. Parts leave the plant ready to use, not as raw mouldings that your line then has to process.

Blow molding is produced in our Thailand and China facilities and managed from Canada, backed by over 30 years of manufacturing experience. Our quality system is IATF 16949:2016 certified, which is built on all ISO 9001:2015 requirements, and parts are checked against GB/T 13510. More about Meco.