As the core equipment for the production of hollow plastic products, extrusion blow molding machines occupy an important position in the plastic processing industry due to their unique molding principles and structural designs. Their characteristics are mainly reflected in multiple dimensions such as material adaptability, molding capacity, production economy, automation level, energy consumption and environmental protection, and application scope, which are analyzed in detail below.

I. Wide Material Adaptability, Compatible with Multiple Types of Resins

Extrusion blow molding machines have extremely strong material compatibility, capable of processing various thermoplastic resins and functional modified materials, covering four major categories: general-purpose plastics, engineering plastics, environmentally friendly biodegradable plastics, and high-barrier composite resins. They can also adapt to material models with different melt flow rates (MFR) to meet differentiated molding requirements. Among them, the general-purpose plastics field can stably process high-density polyethylene (HDPE, MFR 0.01-2.0 g/10min), low-density polyethylene (LDPE, MFR 0.1-10 g/10min), polypropylene (PP, including homopolymer, copolymer and high-impact grades), polyvinyl chloride (PVC, both rigid and flexible), etc. These materials have a wide molding temperature range (150-220℃), which can be accurately matched by the equipment’s segmented temperature control system; the engineering plastics field can be compatible with polycarbonate (PC, molding temperature 260-300℃, requiring a special high-temperature die), polyethylene terephthalate (PET, requiring drying treatment to avoid hydrolysis), acrylonitrile-butadiene-styrene copolymer (ABS, high-impact grades suitable for industrial parts), nylon (PA, including PA6 and PA66, requiring moisture-proof processing), etc. The molding of these materials has higher requirements on the equipment’s screw compression ratio and plasticizing efficiency, and special models can achieve uniform plasticization by optimizing the screw structure (such as barrier screws); in terms of environmentally friendly materials, they not only support the processing of biodegradable plastics such as polylactic acid (PLA, molding temperature 160-190℃, requiring control of crystallization rate) and polyhydroxyalkanoate (PHA), but also can process starch-based composite degradable materials, adapting to the trend of environmentally friendly packaging; in the high-barrier field, they can realize co-extrusion molding of barrier layers such as EVOH (ethylene vinyl alcohol copolymer), PA, PVDC (polyvinylidene chloride) with general-purpose plastics, meeting the long-term fresh-keeping needs of food and pharmaceuticals. This wide material adaptability enables the equipment to accurately match the performance requirements of different industries: for example, the chemical industry uses HDPE to process acid and alkali resistant storage tanks (corrosion resistance grade meets GB/T 18475-2001 standard), the food packaging industry uses EVOH/PE multi-layer co-extruded bottles to achieve oxygen barrier (barrier property reaches O₂ transmission rate ≤1.0 cm³/(m²·24h·0.1MPa)), and the medical field uses PC to process high-temperature resistant infusion bottles (capable of withstanding 121℃ sterilization treatment). In addition, the weight-average molecular weight of blow molding grade plastics is usually 20%-50% higher than that of injection molding grade materials, resulting in tighter entanglement of molecular chains, endowing the products with higher impact toughness (notched impact strength up to 10-50 kJ/m²) and environmental stress crack resistance (ESCR test time ≥1000h), which is especially suitable for the production of large-capacity containers above 100L, avoiding damage during transportation and use.

II. Flexible Molding Capacity, Covering Multi-Specification and Multi-Form Products

The molding capacity of extrusion blow molding machines presents the dual flexible characteristics of “full-specification coverage + multi-form adaptation”, achieving full-span coverage from micro to extra-large products in terms of product specifications: in terms of micro products, it can produce precision reagent bottles with a volume of only 5ml (mouth diameter ≤10mm), using micro dies and precise flow control technology to ensure wall thickness uniformity error ≤±5%; small and medium-sized products (50ml-5L) are the most widely used field, and the production speed can be flexibly adjusted according to the model configuration. Single-cavity models are about 30-60 bottles/hour, and multi-cavity (4-8 cavities) high-speed models can reach up to 9000 bottles/hour, adapting to the large-scale mass production needs of fast-moving consumer goods such as beverages and daily chemicals; in terms of large and extra-large products, conventional models can stably produce chemical storage tanks, trash cans, etc. below 3000L. Through lengthening the guide pillar stroke (up to 5-8m) and enhancing the clamping force (≥2000kN), extra-large special models can realize the integral molding of extra-large capacity hollow products up to 5000L (such as large water storage tanks and marine fuel tanks). These products adopt the continuous extrusion parison process, avoiding the strength hidden dangers caused by splicing, and the weld strength can reach more than 90% of the base material. In terms of product form adaptability, the core advantage of the equipment is that it can directly form complex irregular integral hollow products without secondary processing: for example, detergent bottles with integrated hollow handles, where the handle and the bottle body are formed synchronously, with high bonding strength (tensile breaking force ≥500N), avoiding the risk of falling off caused by subsequent bonding; special-shaped air intake pipes and cooling fluid tanks for automobiles can be directly formed with complex structures such as concave-convex ribs and flanges, with dimensional accuracy error ≤±0.5mm, meeting the assembly requirements of the automotive industry. In terms of wall thickness control, the equipment has multiple flexible adjustment mechanisms: conventional adjustment realizes overall wall thickness uniformity control through fine adjustment of the die gap (adjustment accuracy up to 0.01mm); high-end models are equipped with electronic wall thickness control system (EBC), which detects the parison thickness through infrared, feeds back and adjusts the position of the die mandrel in real time, and can realize differentiated wall thickness design of different parts of the product (such as thickening the stress-concentrated parts such as bottle shoulders and bottle bottoms by 20%-30% and thinning the main body of the bottle), ensuring strength and saving raw materials, with the raw material utilization rate increased by 10%-15%. In addition, the equipment can realize the molding of functional composite products through multi-layer co-extrusion technology (2-6 layers). For example, the “PE/EVOH/PE” three-layer co-extruded bottle for food preservation has an EVOH barrier layer thickness of only 0.05-0.1mm, which can achieve oxygen barrier effect, and the fresh-keeping period is 3-5 times longer than that of single-layer PE bottles; the “PP/PA/PP” three-layer bottle for chemical packaging can block the penetration of organic solvents, suitable for the packaging of volatile reagents such as acetone and ethanol. At the same time, the equipment can stably form thin-walled hollow products (such as disposable beverage bottles) with a wall thickness of 0.2-0.3mm, which is difficult to achieve by injection blow molding, because the parison of injection molding cools quickly, and thin-walled molding is prone to defects such as lack of material and shrinkage marks.

III. Outstanding Production Economy, Significant Cost Control Advantages

Extrusion blow molding machines form a dual advantage of “low initial investment + low operation loss” in production cost control, greatly improving the production economy of enterprises. In terms of initial equipment investment, compared with injection molding machines and injection blow molding machines of the same capacity, extrusion blow molding machines have significant cost advantages: when molding conventional hollow products below 5L, the equipment cost of extrusion blow molding machines is only 1/3-1/2 of that of injection molding machines (for example, the cost of a 5L bottle production line with a capacity of 1000 bottles/hour is about 200,000-300,000 yuan for extrusion blow molding machines, while that of injection molding machines is 600,000-800,000 yuan); the gap in mold cost is more obvious. Extrusion blow molding only requires one set of female molds (including mold cavity and cooling water channel), with a cost of about 20,000-50,000 yuan/set, while injection blow molding needs to be equipped with two sets of molds: parison injection mold and blow molding mold, with a total cost of 80,000-150,000 yuan/set. Moreover, the processing cycle of extrusion blow molding molds is shorter (15-25 days vs 30-45 days for injection blow molding molds), further reducing the enterprise’s production cycle cost. This low-investment feature enables small and medium-sized enterprises and start-ups to quickly enter the hollow product market, especially suitable for the trial production needs of multiple varieties and small batches. In terms of operation cost control, modern extrusion blow molding machines achieve high efficiency and energy saving through multiple technical optimizations: the power system adopts servo motors instead of traditional asynchronous motors, reducing energy consumption by 20%-30% (for example, a 100kW servo motor saves 15-25 kWh of electricity per hour compared with an asynchronous motor of the same power); the hydraulic system adopts variable displacement pumps and energy-saving oil circuit design, which automatically reduces the flow rate when there is no load, further reducing energy loss, and the comprehensive energy-saving effect can reach 8%-15%. In terms of raw material loss control, the raw material waste rate can be controlled within 3%-5% through the precise adjustment of parison thickness by the electronic wall thickness control system (EBC); with the closed-loop edge material recycling system, the edge materials generated during production (accounting for 5%-30%) can be directly crushed and re-added to the extruder without secondary granulation, the recycling rate reaches more than 95%, and the performance loss of recycled materials is only 5%-10%, which can be directly used for the main body or non-critical parts of products, greatly reducing raw material costs (calculated by an annual output of 1000 tons, 30-50 tons of raw materials can be saved, and the annual cost can be saved by 240,000-400,000 yuan at a PE raw material price of 8000 yuan/ton). In terms of equipment maintenance and downtime costs, extrusion blow molding machines adopt modular design, and core components (extruder, die, clamping mechanism) can be disassembled and maintained independently. Routine maintenance (such as screw cleaning and die maintenance) only takes 2-4 hours, while the maintenance time of injection molding machines is usually 8-12 hours; the key components of the equipment are made of high wear-resistant materials (the screw is made of 38CrMoAlA after nitriding treatment, with surface hardness up to HV900-1100, and wear resistance increased by 3 times), the service life can reach 5-8 years, and the annual maintenance cost only accounts for 1%-2% of the total equipment price; at the same time, it is equipped with an automatic lubrication system, which can regularly inject lubricating oil into the moving parts such as guide pillars and lead screws, reducing wear and lowering the fault downtime rate (monthly fault downtime ≤2 hours), ensuring production continuity and further improving the output per unit time. In addition, extrusion blow molding machines require fewer operators. A fully automated production line only needs 1-2 operators (responsible for monitoring equipment operation and raw material supply), while a traditional semi-automated production line needs 3-4 operators. Calculated at an average monthly salary of 6000 yuan per person, the annual labor cost can be saved by 144,000-288,000 yuan.

IV. High Level of Automation and Intelligence, Convenient and Efficient Operation

Contemporary extrusion blow molding machines have fully entered the integrated development stage of “automation + intelligence”, realizing efficient, precise and convenient operation of the entire production process through advanced control systems and supporting devices. In terms of the core configuration of the automatic control system, mainstream models all adopt industrial-grade PLC (Programmable Logic Controller) or embedded microcomputer systems, equipped with special blow molding control software, which can realize precise control of more than 128 key parameters, including extruder section temperature (hopper section, compression section, homogenization section, temperature control accuracy ±1℃), die temperature (±0.5℃), screw speed (0-100r/min, adjustment accuracy ±0.1r/min), parison length (±1mm), blow pressure (0.2-1.0MPa, ±0.01MPa), cooling time (0-60s, ±0.1s), etc. All parameters can be displayed, stored and called in real time, and up to 1000 sets of process parameter formulas for different products can be stored. When changing products, only one key call is needed, and the switching time is ≤10 minutes, greatly improving the production efficiency of multiple varieties. In terms of the configuration of automatic auxiliary systems, the equipment can realize a fully automated closed loop from raw material input to finished product outbound: the raw material supply link is equipped with an automatic feeding machine (vacuum feeding, feeding capacity adjustable 0-500kg/h) and a raw material dryer (for hygroscopic materials such as PET and PA, drying temperature adjustable 80-160℃, dew point ≤-40℃), avoiding dust pollution caused by manual feeding and raw material moisture absorption; the molding link is equipped with automatic clamping, automatic blow molding and automatic cooling systems, without manual intervention; the post-processing link integrates automatic demolding, automatic trimming (using rotating knife or ultrasonic trimming, trimming accuracy ±0.2mm), automatic detection (visual inspection system, which can identify defects such as uneven wall thickness, lack of material and scratches, detection accuracy 0.1mm, defect recognition rate ≥99%), automatic palletizing (palletizing speed 10-20 pieces/minute, stacking height up to 1.8m) and waste automatic conveying system (edge materials are directly crushed and sent back to the extruder hopper). Some high-end models also have automatic roll changing and loading/unloading reel functions, adapting to the needs of continuous film blow molding production. This fully automated configuration not only minimizes manual intervention, but also avoids human operation errors, ensuring the consistency of product quality in each batch (dimensional fluctuation ≤±0.3mm, appearance qualification rate ≥99.5%). In terms of intelligent upgrading, high-end extrusion blow molding machines have realized “data-driven + remote control”: through the industrial Internet module equipped with a remote monitoring system, operators can view real-time equipment operation parameters (output, energy consumption, temperature, pressure), production progress and fault alarm information on mobile phone APP or computer terminals, realizing remote control; the data analysis system can automatically count production data (daily output, reject rate, raw material consumption per unit product, energy consumption), generate production reports, and provide data support for enterprise production scheduling and cost accounting; the intelligent adaptive adjustment function can automatically fine-tune process parameters (such as screw speed and temperature) according to changes in raw material characteristics (such as melt flow rate) and ambient temperature fluctuations, ensuring molding stability; the fault diagnosis system has a built-in database of more than 1000 common faults, which can real-time identify fault types (such as screw blockage, die leakage, cooling system failure) through sensor data, and display fault causes, troubleshooting steps and solutions on the human-machine interface, with fault location time ≤5 minutes, greatly shortening the maintenance cycle. In terms of operation convenience, the equipment all adopts 10-15 inch color touch screen human-machine interface, supporting multi-language switching such as Chinese and English. Parameter adjustment adopts drag-and-drop or input operation, without professional programming skills; some models are equipped with gesture control or voice control functions, further reducing the operation threshold, and new operators can work independently after 1-2 days of training. In addition, the equipment is also equipped with safety interlock automatic control. When the safety door is not closed, pressure is abnormal, temperature exceeds the standard, etc., the equipment will automatically stop and alarm to avoid safety accidents.

V. Reasonable Structural Design, Stable Operation and High Safety

The structural design of extrusion blow molding machines follows the core principles of “stability and reliability, convenient maintenance, safety and efficiency”, ensuring long-term stable operation of the equipment through scientific structural layout and high-quality component selection. In terms of the overall structural layout, the equipment adopts a modular design concept, independently designing core modules such as the extrusion system, die system, clamping system, blow molding system, cooling system and electrical control system. Each module is connected through standard interfaces, which not only facilitates the transportation, installation and commissioning of the equipment (the hoisting weight of a single module ≤5 tons, on-site installation and commissioning time ≤3 days), but also can flexibly configure modules according to production needs (such as replacing dies of different specifications to realize product capacity switching, replacing multi-layer co-extrusion dies to realize composite product production), improving the versatility and expandability of the equipment. Some models adopt an octagonal body structure, which has a torsional strength increased by more than 25% and an occupied area reduced by 10%-15% compared with the traditional rectangular body, especially suitable for enterprises with limited workshop space. In terms of the structure and material of core components, the screw and barrel of the extrusion system are key, made of 38CrMoAlA chromium-molybdenum-aluminum alloy, after quenching and tempering and nitriding treatment (nitriding layer depth 0.3-0.5mm), with surface hardness up to HV900-1100, having excellent wear resistance and corrosion resistance, and can be adapted to the processing of modified plastics added with glass fiber, calcium carbonate and other fillers; the screw adopts a gradual compression ratio or sudden compression ratio design (compression ratio 2.5-4.5), optimizing the screw groove depth and screw edge width according to different material characteristics, ensuring uniform plasticization of raw materials (plasticization uniformity ≥95%), and avoiding unmelted materials affecting product quality; the barrel adopts segmented heating and cooling (water cooling or air cooling) to ensure precise temperature control. The die system adopts a spiral or coat hanger type flow channel design, and the inner wall of the flow channel is polished (roughness Ra ≤0.2μm), reducing material flow resistance and ensuring the circumferential wall thickness uniformity of the parison (error ≤±3%); the die mandrel and die orifice are treated with wear-resistant chrome plating, with hardness up to HRC60-65, prolonging the service life. The clamping system is the core to ensure molding stability. Mainstream models adopt a four-guide pillar balanced pull-push rod structure. The guide pillars are made of 20CrMnTi material after quenching treatment, surface hard chrome plated, and matched with precision linear bearings, with guiding accuracy ≤0.02mm, ensuring stable and non-offset clamping process; the clamping force can be flexibly adjusted according to product size (50-2000kN). Special models for large products adopt back plate central cylinder drive, with uniform clamping force distribution, avoiding mold deformation; at the same time, it is equipped with double protection of mechanical limit blocks and guide rail safety valve value electronic components. When the clamping force exceeds the set threshold (usually 110% of the rated clamping force), the equipment automatically stops, which can effectively prevent the clamping arm from falling off or the mold from being damaged. In terms of cooling system design, the mold is equipped with spiral cooling water channels, the cooling water flow rate is 0.5-1.5m/s, the cooling area is increased by 30% compared with the traditional straight water channel, the cooling efficiency is increased by 20%-30%, the product cooling time can be shortened by 10%-15%, and the production speed is improved; some models are equipped with an intelligent cooling system, which can automatically adjust the cooling water temperature (5-25℃) and flow rate according to the product thickness, avoiding product deformation caused by uneven cooling. In terms of safety protection structure, the equipment strictly complies with international safety standards such as CE and ISO 13849, and is equipped with a fully enclosed safety guardrail around the body. The safety door is made of tempered glass, which is convenient for observing the production process; the safety door and the equipment operation system realize interlock control. When the safety door is opened, the equipment immediately stops, avoiding operators from contacting moving parts; key parts of the equipment (such as die and extruder discharge port) are equipped with high-temperature warning signs and anti-scald protective covers. The electrical control system is equipped with overload protection, short-circuit protection, leakage protection and other functions, and the hydraulic system is equipped with pressure safety valves, comprehensively ensuring the personal safety of operators and equipment safety. In addition, the equipment is also equipped with a centralized lubrication system, which regularly injects lubricating oil into moving parts such as guide pillars, lead screws and clamping mechanisms through a progressive distributor (lubrication cycle adjustable 10-60 minutes), reducing component wear and prolonging the maintenance cycle.

VI. Wide Application Range and Strong Industry Adaptability

Relying on core advantages such as wide material adaptability, flexible molding and cost economy, the application scenarios of extrusion blow molding machines have deeply covered multiple core industries of the national economy, and formed special solutions for the special needs of different industries, with strong industry adaptability. In the food and beverage industry, it is one of the core packaging equipment, mainly used for the production of various hollow packaging containers: PET/PE bottles in the beverage field (bottled water, fruit juice, carbonated drinks) are produced by high-speed multi-cavity extrusion blow molding machines, with a production speed of 6000-9000 bottles/hour, high bottle transparency and good sealing performance (leakage rate ≤0.1% after capping); HDPE/PP bottles and cans in the food packaging field (edible oil, soy sauce, vinegar, dairy products) have oil resistance and corrosion resistance, and some adopt multi-layer co-extrusion technology to achieve light-proof and fresh-keeping functions (such as olive oil bottles adopting “PE/PA/PE” three-layer structure, light-proof rate ≥95%, extending the shelf life to more than 12 months); snack cans and candy cans in the leisure food field can be formed into containers with special-shaped structures, improving product aesthetics. In the daily chemical industry, it adapts to the packaging needs of various detergents, cosmetics and personal care products: HDPE bottles for detergents (laundry detergent, dish soap, shampoo) can be formed into structures with integrated handles, easy to use, and have strong chemical corrosion resistance (can withstand long-term contact with surfactants); PETG/ABS bottles for cosmetics (face cream, lotion, perfume) have excellent transparency and surface gloss, and can achieve frosted, printed and other appearance effects through mold textures, meeting the aesthetic needs of high-end cosmetics; the hose matching caps for personal care products (toothpaste, body wash) are produced by small extrusion blow molding machines, with high dimensional accuracy, adapting to the sealing requirements of hoses. In the medical industry, in response to the high cleanliness and high safety requirements of pharmaceutical packaging, special extrusion blow molding machines adopt stainless steel bodies, food-grade greases, and are equipped with clean room special covers, which can produce medical infusion bottles (PC material, capable of withstanding 121℃ high-pressure steam sterilization), medical reagent bottles (PET material, sealing performance meets GMP standards, water vapor transmission rate ≤0.5g/(m²·24h)), medical device housings (such as ventilator components, infusion pump housings), etc. The equipment operation process has no dust pollution, and the products meet international medical standards such as USP and EP. In the chemical industry, it is the core production equipment for corrosion-resistant hollow containers, mainly producing various chemical storage tanks, reagent bottles, pesticide bottles, etc.: large chemical storage tanks (500-5000L) are made of HDPE material, integrally formed without welds, corrosion resistance grade meets GB/T 18475-2001 standard, and can store acid and alkali reagents such as sulfuric acid (concentration ≤98%) and sodium hydroxide (concentration ≤30%); small chemical reagent bottles (100ml-5L) are made of PP/PE material, with anti-leakage and anti-impact performance, adapting to the packaging of volatile reagents such as acetone and ethanol; pesticide bottles adopt high-barrier materials (such as EVOH/PE co-extrusion), which can prevent the volatilization of effective pesticide components and avoid pesticide penetration and environmental pollution. In the automotive industry, adapting to the development trend of automotive lightweight and integration, it produces various automotive hollow parts: automotive fuel tanks (HDPE material, with oil resistance and impact resistance, can withstand temperature changes from -40℃ to 80℃), cooling fluid tanks (PA material, high temperature resistance above 120℃), intake manifolds (ABS material, significant lightweight effect, 40%-50% lighter than metal manifolds), power steering oil tanks, etc. These products have high dimensional accuracy (error ≤±0.5mm), and can be directly assembled with other automotive parts, improving the overall vehicle assembly efficiency. In the agricultural field, it is mainly used for the production of hollow products related to agricultural irrigation and breeding: irrigation water storage tanks (1000-3000L, HDPE material, UV aging resistance, service life ≥10 years), pesticide sprayer tanks (PP material, pesticide corrosion resistance), breeding oxygen cylinder housings, etc.; in the construction field, it can produce construction water supply and drainage pipe fittings (such as PE pipe joints), hollow wall panels, thermal insulation material housings, etc., with weather resistance and aging resistance, adapting to the outdoor use environment of construction. In addition, extrusion blow molding machines are also used in high-end fields such as aerospace, shipping and new energy, such as producing lightweight hollow structural parts for aerospace, marine fuel tanks, and new energy vehicle battery housings. By adopting high-performance engineering plastics and precision molding technology, they meet the special performance requirements of high-end fields.

VII. Limitations Supplement

Although extrusion blow molding machines have many core advantages, they still have three core limitations due to the constraints of molding principles and technical characteristics, which need to be compensated by supporting equipment or process optimization. First, the dimensional accuracy of the product mouth is relatively low, making it difficult to adapt to precision scenarios with ultra-high sealing requirements. The mouth of extrusion blow molding products is formed by natural cooling and setting after parison blow molding. Affected by factors such as parison shrinkage and blow pressure fluctuation, the inner and outer diameter dimensional accuracy of the mouth is usually ±0.1-0.2mm, while the mouth of injection blow molding products is formed by injection molding, with dimensional accuracy up to ±0.02-0.05mm. Therefore, extrusion blow molding products are difficult to meet the ultra-high sealing requirements of high-end precision packaging (such as medical freeze-dried preparation bottles and high-end cosmetic vacuum bottles). In such scenarios, the mouth is prone to leakage and poor sealing, leading to product deterioration or failure. To address this limitation, a composite process of “extrusion blow molding + post-processing of the mouth” can be adopted. Through precision turning of the mouth by a lathe or secondary setting with a mouth molding mold, the dimensional accuracy of the mouth can be improved to within ±0.05mm to meet the sealing requirements, but it will increase processing procedures and costs. Second, the generation rate of edge materials during production is relatively high, requiring a complete supporting recycling system. In conventional extrusion blow molding production, due to the need to reserve a certain margin for the parison for trimming (removing excess material at the mouth and excess material at the clamping line), the generation rate of edge materials is usually 5%-30%. The specific proportion depends on the complexity of the product shape (the proportion of edge materials for special-shaped products can reach 25%-30%, and that for regular bottles and cans is about 5%-15%). Without a supporting recycling system, it will not only cause waste of raw materials, but also generate environmental pressure; even with a recycling system, the performance of recycled materials will have a loss of 5%-10%, which cannot be directly used for products with high performance requirements (such as medical bottles and food-grade packaging), but only for non-critical parts or low-requirement products. The current industry optimization solutions are to adopt waste-free blow molding technology (reducing trimming margin through precise design of parison length and die size) to control the generation rate of edge materials within 3%, or to use special recycling modifiers to improve the performance of recycled materials and expand the application range of recycled materials. Third, clamping lines are likely to form on the product surface, affecting the appearance quality. The clamping process of extrusion blow molding is the closing of two half-molds, and a clear clamping line will be formed at the clamping position of the parison (line width usually 0.1-0.3mm). The surface roughness at the clamping line is Ra ≥0.8μm, which is much higher than that of other parts of the product (Ra ≤0.2μm). For products with extremely high appearance requirements (such as high-end cosmetic bottles and automotive interior parts), the clamping line will seriously affect the aesthetics and texture of the product. To solve this problem, the width of the clamping line can be controlled within 0.05mm by optimizing the mold structure (using precise centering positioning pins to reduce the clamping gap) and adjusting the clamping pressure and speed (avoiding excessive extrusion of the parison at the clamping position). At the same time, the clamping line can be treated by post-processing processes (such as polishing, grinding and spraying), but it will increase processing costs and production cycles, and reduce production efficiency. In addition, extrusion blow molding also has shortcomings in the molding stability of thin-walled and ultra-small capacity products. Thin-walled products (wall thickness ≤0.2mm) are prone to defects such as uneven wall thickness, lack of material and depression. Ultra-small capacity products (≤5ml) are difficult to mold, requiring extremely high equipment accuracy and process parameters, and conventional models are difficult to produce stably.

Conclusion

Overall, relying on core advantages such as wide material adaptability (covering four major types of resins: general-purpose, engineering, environmental protection and high-barrier, adapting to the performance requirements of different industries), flexible molding capacity (realizing full-specification product coverage from 5ml to 5000L, directly forming complex irregular integral structures, with precise wall thickness adjustment capability), outstanding production economy (initial equipment and mold investment is only 1/3-1/2 of that of similar injection molding equipment, low operation energy consumption, less raw material loss and low maintenance cost), high level of automation and intelligence (fully automated closed-loop production, with remote monitoring, intelligent adaptive adjustment and fault diagnosis functions), and stable and safe structure (modular design, high-quality wear-resistant components, multiple safety protections), extrusion blow molding machines have become the mainstream equipment in the field of hollow plastic product production. Especially in the production of large-capacity containers, complex special-shaped products and low-cost mass-produced products, they occupy an irreplaceable position. Their existing limitations such as low mouth accuracy, high edge material generation rate and surface clamping lines cannot be completely avoided, but can be effectively compensated by means of composite processes such as “extrusion blow molding + post-processing”, waste-free blow molding technology and mold optimization, reducing the impact on production. Therefore, they are particularly suitable for small and medium-sized enterprises that are sensitive to costs, have diverse product specifications and flexible production scales, and can also meet the large-scale mass production needs of large fast-moving consumer goods, chemical and automotive enterprises. From the perspective of industry development trends, with the tightening of global environmental policies and the advancement of intelligent manufacturing, extrusion blow molding machines will upgrade in three directions: first, environmental protection, further improving the processing adaptability of biodegradable plastics and recycled plastics, optimizing energy-saving technologies (such as servo motors and electromagnetic heating), reducing unit product energy consumption, and supporting more efficient edge material recycling systems to realize green production; second, intelligence, deeply integrating industrial Internet and artificial intelligence technologies to realize self-learning and self-optimization of process parameters, improving molding stability and product quality consistency, and realizing the whole life cycle management of equipment through digital twin technology; third, high-endization, improving equipment accuracy, breaking through the molding technical bottlenecks of thin-walled, ultra-small capacity and ultra-high sealing requirement products, and expanding applications in high-end fields such as aerospace and high-end medical care. In the future, with the continuous implementation of these technologies, the advantages of extrusion blow molding machines will be further highlighted, and the application range will continue to extend to more high-end fields, providing core equipment support for the high-quality development of the hollow plastic product industry.