Hong Kong Plasticity Conference

The 2013 Plasticity conference will be held in Hong Kong in early June, which will focus on the plastic waste problem. The first conference was held on United Nations Sustainable Development Forum in the same term last year.

This conference will be held on June 6. It will explore the solution to the problem of waste plastics. The keynote speakers include Lu Gonghui, the deputy director of Hong Kong Environmental Protection Bureau, and Mike Biddle, founder of plastic recycling enterprise MBA in California and winner of Gothenburg Award for Sustainable Development.

This forum is organized by non-profit organization, Ocean Recovery Alliance, which has offices in California and Hong Kong. The focus of this league is problems of marine pollution, including waste plastics. The American Chemistry Council is also the partner support of this conference.

“By 2013, 40% of the world’s sea surface is covered by some form of floating plastic garbage, which is thought-provoking. More and more companies and organizations are paying attention to the solution to plastic waste problem”, said the organization.

The event will also include the speech of Bayer Material Science and Taiwan Plastic Industry Technology Development Center.

The sponsor said the major intent of this conference is to collect retailers, policy makers, manufacturers and other personages of all circles to discuss the problem.

PP Injection Molding

Throughout 2008 the domestic PP market, the overall PE with similar, but also from the initial price has experienced a smooth, and then start a slow market, and then prices skyrocketing, and then to the market gradually cooling, the sharp reversal of collapse, and finally to the vulnerable process. PP injection molding the first three months of the market has been in the doldrums of the state, approaching the price of pellet powder, the market turnover is very bleak. To the market to start in mid-April, the upstream crude oil prices continue to climb, propylene ferocious price rise, because the cost pressures, petrochemical manufacturers continue to push up prices, market speculation traders warm gradually rising to the May and June were the market price of PP have been had risen to an unprecedented high level, but the market did not fully follow up the High prices, the reaction to the market turnover has not unprecedented amplification, so this wave of market can only go so far, prices in mid to late July has begun, vibration downlink and continued until September; until October, the international financial crisis to the global impact has unlimited zoom, crude oil dropped sharply, the domestic PP market could not escape a fall unprecedented shrinkage of market demand, petrochemical factory inventories high, prices have diving, exacerbated traders panic mentality, PP injection molding market prices plummeted, until the late November only to stabilize the price bottomed, but the rebound is not the strength to the market is still low in mid-December concussion . Center for China’s chemical market analyst network that: In view of the current form of the domestic economic downturn and lower reaches of real estate, automobiles and household appliances, such as frozen products industry are still in the period 2009 PP cannot be optimistic about the market, or to vulnerable main concussion

Injection blow molding

plastic bottle molding Medicines are the largest production and sales of medical plastic products. With the rapid development of the domestic medical industry, the domestic consumption of medicine bottles will show substantial growth. In this regard, the domestic equipment manufacturers should be as hollow as an opportunity to grasp the development trend of plastic bottles, research and development of new high-performance, high-performance bottle molding equipment, and strive to shorten with the international advanced technology and equipment gaps.

The main molding equipment

Plastic bottle blow molding equipment, according to shape in different ways, mainly divided into three types: extrusion blow molding machine, injection blow molding machine, as well as to “squeeze – la – blow” or “Note – la – blow” molding machine. Extrusion blow molding and injection blow molding machine is mainly used for production of medicinal small plastic bottles, to “squeeze – la – blow” or “Note – la – blow” molding machine is used in the production of large bottles. At present in China, Applied Extrusion blow molding and injection blow molding machine manufacturing enterprises of plastic bottles up to.

Extrusion blow molding machine

Extrusion blow molding machinery (including the blow mold) and a lower cost, such as forming the same product, blow molding machinery, injection molding machines cost about 1 / 3 or 1 / 2. At the same time, production costs are also low. As the parison is at a relatively low pressure through the extrusion die molding and low pressure (mostly 0.2 ~ 1.0MPa) under Inflation, and therefore less residual stress in the product, and the resistance to tensile, impact, bending and the environment high performance for various contingencies, with good use of the performance. As the blow mold cavity block only by composition, so by simply adjusting the nose or the extrusion die exit gap conditions, the body can change the bottle wall thickness. In addition, because blow mold can be set to slide at the end of the module, so the bottom of the bottle-shaped body of a larger design flexibility. Extrusion blow molding the shape can be complex, irregular and the overall style of the product, and therefore more suitable for forming HDPE, PP raw materials for hard plastic bottle.

Injection Blow Molding Machine

Injection blow molding machine mainly used for processing of HDPE, PP raw materials for medicine bottles. Injection blow molding equipment, using a small plastic bottle was generally welcomed by pharmaceutical companies. As the injection blow molding of bottles in the molding process, the device can be injection nozzle bottle of injection molding, thus ensuring the accuracy of bottle; followed by a bottle blow molding machine configured mandrel body, the guarantee of the plastic bottle body shape dimensional accuracy.

Injection blow molding can be used a medicine bottle-step two-station or 3-station injection blow molding machine processing. As the two-station injection blow molding machine the lack of a dedicated off bottles and cooling stations, it is difficult to achieve fully automatic counting packaging, resulting in production efficiency was less than 3-position. Thus, in actual production use more of a three-station machine. The aircraft’s three stations to 120 ° angle into the distribution of an equilateral triangle, the first station for the injection molding station, the second station for the blow molding station, the third station for the off bottles and cooling stations. Three-station can be run simultaneously, producing high efficiency, short cycle can be connected with the conveyor automatic counting packaging, truly the whole process of production of pharmaceutical plastic bottle with the staff of the “no contact” order to ensure product cleanliness. Injection blow molding machine could not be forming the shape of complex products, and the shape of the bottle most of the smaller volume (usually 10 ~ 300ml). However, injection blow molding bottle bottle flatness high sidewall thickness uniformity, in particular, between the bottle and the bottle has good sealing performance can reach to prevent the plastic bottle of medicine and external gases of volatile gases to the bottle penetration performance requirements, which makes this bottle in full compliance with the special requirements of pharmaceutical packaging. State Drug Supervisory Authority as early as in the “Ninth Five Year Plan” period on the proposed use of injection blow molding method of producing high-quality plastic bottles. At present, China imported from abroad medicine bottle injection blow molding production lines up to more than 40, with a total production capacity of about 700 million / year.

“Note – la – blow” molding machine

“Note – la – blowing” PET, PP bottle (for filling liquid medicines) machine is divided into two kinds of one-step and two-step models. One-step model is the parison injection, heating parison, the tensile parison and blow molding processes such as product ejection device in the same row for the efficient equipment. According to molding processes, one-step model is divided into three stations (Aoki of Japan, represented by solid machine) and 4-position (in Japan’s precision machinery as the representative) two kinds of machines. The main difference between the two is: “3-station” refers to the injection with the heated parison parison in a process completed, “4-station” refers to injection with the heated parison parison in the two processes to complete. One-step model does not cause secondary pollution products, and a good product identity. Despite higher prices, but to reach the high cleanliness requirements bottles in recent years, the domestic pharmaceutical companies more inclined to use the one-step “Note – la – blow” bottle molding machine. To this end, some equipment manufacturers in the domestic absorption of foreign advanced technology and intensify the development on the basis of foreign equipment could be replaced by one-step models, and have achieved some results.

Two-step model refers to the injection and stretch blow molding process by an independent two machines separately. The first step: from a common injection molding machine injection molding tube, head tube of the bottle part (bottle, screw) had completed its forming; the second step: The tube on the honeycomb heater or automatic cycle of heating on the heat conveyor thermostat, and then moved to the stretch blowing process using compressed air to blow molding. Than the flat bottle, seal well and fast product development, mold fees and costs, lower prices are “two-step” models of advantages, but due to injection blow molding tube and the step-wise, the product identity is poor, and easy to pass pollution, difficult to check by bacteria.

R & D direction

Plastic bottle forming machine up to other hollow plastic molding equipment, specifications of small, fast, high precision and high efficiency. The main direction of its R & D high-speed, high efficiency, energy saving, environmental protection and adaptive quality control.

All-electric one-step “Note – la – Blow” Blow Molding Machine

The recent development of a high response AC servo motor-driven dosing pumps energy-saving systems, injection molding machine has been successfully applied. Similarly, injection blow molding, “Note – la – blowing” plastic bottle molding equipment of the main system power drive can also be portable such systems. The system pressure and flow through precise closed-loop control of servo motor to achieve the energy requirements of the implementing agencies the best matching and automatic adjustment, so as to achieve energy efficiency, improve performance and reduce environmental pollution multitude of purposes.

All-electric one-step “Note – la – Blow” Blow Molding Machine for its precise location, speed, no vibration, high self-cleaning as well as the advantages of high efficiency, high-performance plastic bottle molding machine into the development of hot. The key to development of aircraft types is to achieve turntable body clamping preform molding, stretch blow molding and injection-locking mechanism simultaneously plasticizing institutions of all-electric drive. All electric molding preforms and stretch blow mold body simultaneously locking mechanism design, refer to the all-electric injection molding machine clamping. For the all-electric injection of plasticized bodies, can be completely copy all-electric injection molding machine plasticizing bodies. It can be said, with the all-electric injection molding machine mature technology, which is developing electric-step “Note – la – Blow” Blow Molding Machine is not very great difficulty.

At present the domestic market all-electric one-step “Note – la – Blow” Blow Molding Machine, with Shanghai Machinery Co., Ltd. Ace must be represented by models developed by ASB-15N/10E. The machine uses closed-loop servo system, than the original hydraulic system greatly improved the stability of control, saving up to 40% and a change of hydraulic transmission fluid oil (hydraulic system valves, piping, etc. prone to leak, the use of age is even worse than the old equipment) on the environment, product contamination.

High-speed, high-quality PET, PP preform injection gasoline-electric composite body

The performance of injection plastics sector is directly related to the quality of preforms. Reciprocating screw injection of common plastics, as before and after the plasticizing quality and inconsistent, leading to inconsistent quality preform; and also because the two can be made between injection and plasticizing the same time, reducing production efficiency. Note the use of composite plastics extrusion injection system (to be plasticized with the injection of two kinds of functions from the conventional one component is divided into two parts, namely, an independent servo motor-driven extruder screw plasticizing and hydraulic plunger independent injection, both of the Inter-Noninterference), then to stabilize the PET, PP melt axial temperature and thus to achieve consistency of quality plastics, but also greatly enhance productivity.

Improve the forming rate and yield

Improve production efficiency is the domestic pharmaceutical packaging container injection blow molding equipment, the key to development. Vinda Jiangsu Machinery Co., Ltd. successfully developed the domestic first-step three-station injection blow molding machine, has in recent years is based on 100 production lines each year the size of rapid development. Use of Ouida’s MSZ60L models, the production 30ml × 12 cavity typical of conventional plastic bottles production cycle of only 10S. Zhangjiagang Green Central degradation of complete sets of equipment Co., Ltd to absorb European NOVVAPAX, BEKUM of the technology, has developed solid particles suitable for the production of medicinal polyolefin bottles of high-performance 3 station injection blow moulding machine, the shortest production cycle up to 8s. Machine dual-link mechanical protection, turntable with the opening and closing movements synchronous operation mode, greatly shorten the cycle; use of plasticizing screw extruder, screw aspect ratio increased to meet the transparent PP, PE, PS, PC and other hollow products process needs; preform temperature uniformity, product unparalleled line; with a single beam clamping structure, convenient and quick replacement of mold; machines simple shape is conducive to purification, in line with GNP specifications. Panan triple Pharmaceutical Packaging Co., Ltd. for the production of generic pharmaceutical plastic bottles technical problems, has created a unique high-pressure gas thermostat technology. The technology uses electromagnetic speed control system to replace the inverter system, reducing the machine size, reduced power consumption, and improved use of equipment performance and product quality.

Development of high-performance mold

Although in recent years, many domestic enterprises in the “Note – la – blowing” equipment to spend more energy and money, so that equipment has been reach or approach international advanced level, but because of neglect and efficient accompanying “Note – la – blowing” mold development, and therefore can not play its due role in equipment. This is a bottleneck restricting development of the industry. For relevant domestic enterprises, in order to develop a high level of “Note – la – Blow,” Die, you must use an advanced computer-aided engineering (CAE) technology to the “Note – la – blowing” process simulation, which avoided by experience, trial and error and by way of amending the blindness brought about the end, the mold material, mold cavity ratio of the different blowing Zhang, hot runner nozzle structural design, as well as temperature control, etc. have access to the most optimal results. Multi-layer co-extruded hollow plastic bottle molding machine

Multi-layer composite bottle has to avoid the light transmission and to prevent the infiltration of gases such as C02 performance, to meet certain require special storage conditions required for bio-engineering drugs, has become a major pharmaceutical packaging market, one of the products. For example, the 3-layer co-extruded plastic bottles (the most outer layer of the PA material, the middle layer of PET material, the inner layer of PC material), with good transparency and tightness can be isolated from moisture and oxygen, not only for routine blood products, such as human serum albumin and protein, collagen fibers and other products directly to packaging, but also can be used as a variety of bio-engineering drugs, such as interferon, monoclonal antibody drugs, a variety of packaging materials.

Multi-layer co-extrusion Blow molding machine bottle blow molding machine and other than the greatly increased complexity, especially in the nose design. Current research and development for the aircraft types, the main focus on the following three points: (1) to study the use of a certain range of co-extrusion head to meet the needs of different materials, different layers, and head diameter and other requirements. The nose is a multi-layer co-extruded hollow plastic molding machines of the “heart”, its performance should reach: control at every level to achieve the best condition to achieve the perfect circle and lateral material distribution; can not influence the distribution of the processed material change a wide range of plastic raw materials. Spiral mandrel composite systems are highly adaptable, multi-layer co-extruded nose should be the priority to the use of the system. (2) research portfolio of packaging systems, which can be customized according to different materials which might allow the number of combinations of nose. (3) research-based mechanical procedures in order to determine the number of molding stations, the production speed and size of product design platform.

Conclusion

Medicine bottles are the largest production and sales of medical plastic products, but also a rapid growth of large medical plastic products. The product is inseparable from the production of high-performance, high-performance hollow molding equipment (including mold). As the domestic Blow Molding Equipment, compared with foreign equipment, there is not a small gap, therefore, the domestic hollow plastic molding equipment manufacturers can only grasp the development trend of the bottle, research and development of new plastic bottle molding equipment, in order to gradually narrow the gap with foreign manufacturers , and in the market with rival.



Blow Molding Parts

We are a world class blow molding parts leader in the design and manufacture of custom blow molds & blow molded parts. Leading the blow molds industry for more than a quarter century, we have set the standard for Design Innovation of blow molds, Precision Blow Molds Manufacturing, and Customer Support.

We Design Blow Molds, Quick Change Blow Molds, Blow Molds Manufacturer, variety of Blow molds, 2D and 3D design for Blow Molds using solid modeling, Blow Molds of plastic bottles, we supply a wide variety of Blow molds

Our Blow Molds are designed and manufactured with state of the art engineering systems and blow molds manufacturing equipment. We have been building blow molds since 1978.

DESIGN AND APPLICATION

The rotamoulding process offers more design freedom and flexibility of form than many other moulding techniques. like injection blow molding, Injection Molded Plastic Parts
Despite its simplicity and economical tooling, surprisingly complex forms can be achieved that are unobtainable with other processes. The advantages are many and varied

  • Rotamoulding does not involve high pressures, hence the low tooling costs. When rotational moulding is used as an alternative to injection or blow moulding, tooling cost can be reduced by as much as 80 – 90%.
  • Low tooling costs enable productions runs of less then 100 to be realised, and make economical prototyping possible, particularly for blow moulding. In addition, experimentation with different wall thicknesses, alternative polymers and a wide variety of surface finishes is not prohibitive.
  • but not every plastic injection molding parts can be made in rotamoulding process, some of the need to made in plastic injection molding process, some of them made in blow molding. if you need to reduce your plastic injection molding tooling cost, then find mold manufacturer China companies to support you.
  • Since mouldings do not have to withstand high pressure during the rotational process, they are virtually stress-free. In comparison with high-pressure moulding processes, they are less likely to suffer stress cracking in use.
    It’s easier to make changes to a rotational mould than to other types of mould, with the advantage that lead times can be cut to a minimum. In some cases products can go from CAD concept to production in a matter of weeks. This means that design can reflect market requirements.
    Depending on the design, Hollow shapes can be moulded without seams, sprues or ejection marks.
    Wall thickness normally remains constant throughout the entire moulding and can be even greater than 10mm. If required, it can be Increasedwhere service stress is likely to be applied.
    Screw threads bosses and metal inserts can easily be moulded in, reducing expensive secondary fabrication.
    Excellent load bearing properties can be achieved with twin-wall cavities or by foam-filling the spaces between the walls.
    Rotamoulding is ideal not only for tough rigid shapes but also for flexible mouldings with deep undercuts, used in the manufacture of inflatable products such as rescue crafts and toys.
    Engineering resins can now be rotationally formed to produce mouldings for continuous service in both high and low-temperature environments.
  • Both symmetrical and asymmetrical designs can be formed as well as complex, one piece mouldings impossible with other processes.
    Mould surfaces can be texturedfor safety or aesthetic reasons, or carry moulded-in company logos, information or diagrams.
    Rotamoulding offers great flexibility of size, from small medical squeeze bulbs to bulk storage tanks of over 15,000 litres. However, it is best suited to medium to large mouldings.
    Rotationally moulded engineering polymers can produce high strength, minimum weight mouldings at the lowest possible cost compared with other engineering polymers moulded by other processes.
  • Rotamoulding is one of the few processes that permits undercuts, and if these are small, draft angles can be avoided. In addition, if the design does not necessitate an internal male core, no angled taper is needed.
    It’s easier to make changes to a rotational mould than to other types of mould, with the advantage that lead times can be cut to a minimum. In some cases products can go from CAD concept to production in a matter of weeks. This means that design can reflect market requirements.
    No sprues or runners means low materials wastage. Excess material that is cut from a finished component can be recycled immediately in the factory. In addition, waste-free design can be built into a mould, such as a container and lid moulded together and separated afterwards.
    Rotamoulding offers designers the benefit of recyclability. Mouldings tend to be in one thermoplastic polymer, enabling designers to plan for material recovery.

If you are looking for Rotamoulding service, blow injection molding service, and plastic injection molding service, please contact us.

Increase Your Blow Molding Machine

In the early days of industrial blow molding, the processor had quite a few obstacles to overcome, many of which formed bad habits.

Here are a few that come to mind – let’s call these industrial blow molding then:
 
1. Material and color changeover times ranged from 8 hr to several days depending on the color and material.

2. Poor head designs led to machine downtime and expensive repairs. Many of these occurred every six months or so, amounting to weeks of downtime.

3. Long periods of downtime were spent just waiting for the service tech to arrive to begin to solve the problem.

4. Very basic manuals, schematics, and sequence of operation did not necessarily pertain to your machine as built. Since there are tons of old machines with many “fix up” repairs over the years, these changes have not been recorded in most cases.

5. All of the older machines were semi-automatic and relied on an operator to close the gates and restart the cycle. This gave very unpredictable control of cycle times. And there were no part takeout systems.

6. Mold changeover took a minimum of a full day or even two. Often this also included changing head tooling.

7. Setups from product changes always seem to cause issues, even though the same changeover was done just last week.

8. Cycle times depended on a combination of:

  • parison drop time,
  • press closing time,
  • blow time,
  • exhaust (vent) time,
  • decompression time,
  • clamp opening,
  • gate opening,
  • manual part removal,
  • gate closing,
  • clamp moving to pre-close position.

Due to the many factors involved, these obstacles limited the number of changeovers and different types of parts that could be run on a machine.

Fortunately, developments in machine and processing technologies have removed many of these obstacles, putting blow molders in a better position to keep the machines and profits up.

Let’s look at industrial blow molding now:

1. Current head technology allows color changes in about 20 min to a maximum of 1.25 hr for the most difficult changeover. Since some blow molders make up to three color changes a day, the savings are huge and drop right to the bottom line.

2. Heads now on the market require little repair or maintenance. The industry has switched from sensitive mica-band head heaters to extruded aluminum and Calrod heaters.

After five years of use, these heaters have not experienced one blow-out as compared with hundreds on the mica band heaters, cutting replacement cost and downtime. Further, a properly designed head will eliminate potential galling from metal-to-metal rubbing on the moving internal sections of the flow paths of plastic materials.

This was a major cause of overly long color/material changeover times. There are heads on the market that allow disassembly/cleaning/assembly to change color or material within 1 hr.

3. It is still not uncommon to have to wait for a service tech to arrive at your plant to fix your machine. But I have found out that about 80% of machine problems today are due to improper setup. These types of problems can be solved by technology that links the supplier directly to your machine for troubleshooting.

Most issues can now be identified and resolved in 1 to 2 hr.

4. Machine manuals can now be made viewed on the machine operator’s computer screen. No need to try to find the original paper manuals that are stored in a locked supervisor’s office at 3 am.

5.   Automated Part Takeout has now become a standard component of the blow molding machine. Automation gives a consistent cycle time. In addition, it now makes sense to include a part-holding fixture with the PTO system. In dual-head operations, the holder prevents the part from dropping until the operator is finished with the first part. The gain here is the possible elimination of a second operator for each shift.

6. Molds are now designed with quick-change connections for water, air, and hydraulics. Some processors now make complete mold changeovers in 15 min. This means more uptime and more profit in your pocket.

The costs to accomplish faster mold changes are nominal. Look at mold positioning gadgets like locater hangers.

In many cases, air, water, and hydraulic manifolds mounted directly on the mold will save many hours thanks to fewer connections to be made. Keep your tools on a wagon for the next changeover. This cuts down on walks across the building to get the necessary tools.

The other area of changeover is the head tooling. It’s usually hot, heavy, and large. Simple tables or adjustable stands to support and guide the tooling into place will save time and make changeovers safer.

How much is all this worth?

Every second saved adds directly to your bottom-line profit. For example, if we can save 3 sec on a 60-sec cycle time with a dual-head operation, and the mold runs for 7000 hr/yr, the benefit is 30,000 more parts/yr.

How do we accomplish this?

Make sure there is no more than 1 sec between starting drop of parison and the extruder reaching shot size. It might be possible to bring the pre-close position closer to the mold-close position. This alone could save 1 sec.

Air blow and vent times are usually the longest parts of the cycle. Shorten the time for air blow and see whether that affects the ability to make an acceptable part.

Check the vent/exhaust time of the air inside the part. Make sure the quick-exhaust valve is large enough to vent out a large amount of air in 5 to 6 sec or less. (I have seen this take 10 to 20 sec or longer with an improperly sized exhaust valve.)

Have the part take out start to remove the part from the mold prior to the gate opening. Only open the mold platens just enough to get the part out with the part take out.

On a single-head machine colors changed from white to dark blue and back to white. Both of these color changes were achieved in a total of about 30 shots (30 min)—for not one, but two color changes.

Blow Molded Parts Manufacturing

How to make Blow Molded Parts

First time parison programming for a new part can be lengthy and tedious.

Here’s some advice on making the process a bit easier:

The accumulator head is the most important component of an industrial blow molding machine. Likewise, forming a parison profiled to the proper wall thickness for a given part is mandatory to get consistent parts that meet specifications.

Blow Molding Machine

On dual-head machines with two molds of the same or different products, it is advisable to run just one head first to develop the necessary processing points. This will make it quicker to accomplish good parts.

First-time parison programming for a new part can be a very lengthy and difficult process. It all depends on what type of part is being made: Is it round or rectangular with a small height? What about the blow ratio of the parison into the mold areas? Those are just two of the issues that need to be addressed.

Then relate those factors to the original wall thickness of the parison at various segments along its length. Blow molding machine and head performance and optimal settings are usually different from machine to machine. Every machine has its own personality, and you need to learn these differences. The key issues are how to set up the parison length and profile points to make an acceptable part.

First, estimate the length of parison required. Measure the mold length and the distance from face of the tooling mandrel to the top of the mold. Determine the additional parison length below the bottom of the mold required for pre-pinch, blow-pin stand, and parison spreader (depending on what is required to make the part). Then determine the layflat of the parison to size head tooling.

Next, determine the actual length of the parison. Experience is especially important when doing this for a new mold and part design. Refer to any similar parts previously produced to assist in factoring the proper shot size. It is better to be longer on the parison than too short. If you have a short shot you’ll wind up with a glob of plastic lying in the bottom of the mold or floor. Making an actual part will enable you to make critical changes on the next shots.

This is not yet the time to configure any parison profile steps. Instead, check the finished weight of the part and measure its wall thickness in critical areas. Review those results and consider areas that require major profile changes.

Make sure the parison drops straight on a consistent basis.

Now consider how much space is needed between the bottom of the head tooling face and the top of the mold. Round parts can allow the tooling face to be closer to the top of the mold. This minimizes the amount of top and bottom flash. But flat panels and molds with small shut height (thickness) must be farther away from head tooling due to parison arching angles back to the head tooling.

This might require using a pre-pinch unit to “balloon up” the parison diameter. (It’s like a blown up bag.)

The parison must be long enough to allow pinch bars to seal the parison bottom and clear the mold. The job might also require parison spreader pins (or blow-pin movement for offset necks). These features could require either longer parisons or cutouts in the molds for the spreader pins. Once you pre-pinch the parison, you might need to slow closing of the press to allow the inflated parison to fit into the deep-draw areas of the mold.

If you are running a dual-head machine with two molds of the same or different products, run just one head first to develop the necessary processing points. This will make it quicker to make good parts. Once you can make a series of good parts, you can transfer the details and setpoints to the second head if it is the same part on both heads.

Most likely, minor changes will be required for the second head, which can be programmed accordingly.

To estimate the weight of the parison (best guess), determine how much flash might be required on the top, bottom, and sides of the parts. Once you have repeated the parison weight and length for three or four shots, you can start profile programming of the thin and thick parts of the parison and part. It is a time-consuming chore to measure wall thickness in various areas of the part and parison. It will be a great help if the parison can be manually purged out at the proper speed and profile steps to determine the set-up for automatic operation.

Some parison programming units allow you to place a spike (a thick parison numbered point) in a given area that might be too thick or thin. This will enable you to quickly find the correct location (profile numbered point) for the change.

Some systems allow you to accurately trace the actual profile path after the parison is dropped, as compared with the setup profile. This will improve the speed at which you can achieve the correct area thicknesses. It will also indicate places that you are asking the machine to accomplish too abrupt a change in thickness and the mechanical parts cannot react fast enough. That will produce a wide variation in wall thickness in those spots.

Use as many “master” setpoints as needed, but don’t overdo it. There are systems available that allow smoothing of the master points by either holding the original master points’ position or allowing them to “travel” with the smoothing feature. Make only one programming change at a time and stick with it until you are sure it can or cannot accomplish the desired results. Remember the drawdown effect from gravity on the top section of the parison. In most cases, this area must be thickened.

How fast should the parison be pushed out? This certainly will affect parison swell and the total amount of flash. Fast parison drop in most cases will increase the layflat. Trying to vary the parison drop speed is very difficult to control in relation to exact positions along the parison.

In many cases, the mold might stay in the machine only a few days. This is not enough time to set up the proper parison profile. You could make many reject parts trying to get the acceptable part dimensions needed in such a short time in the machine. The saving grace, in many cases, is to ship parts that are on the heavy side to ensure they won’t be rejected by the customer. The negative consequence will be additional costs for the heavier parts, which can eat up your profit.

You may even need to change the head tooling size in order to make an acceptable part. If so, you will probably have to do the above functions all over again with new tooling.

Allen has more than 20 years’ experience in blow molding parts manufacturing. His firm, GC MOLD., provides engineering/consulting services and equipment to industrial blow molders, plastic mold, die casting, metal tooling serce to the ords. Reach him by contact us page. Website: industrialblowmolding.com