The tooling used for bucket injection moulding in China is called China bucket mould or plastic China bucket injection mould. Plastic moulds are made by combining steel plates and other mould parts, coupled to form a monolithic mould, which is then reliably assembled and installed in an injection moulding machine, and the thermoplastic resin is then applied to the desired shape to achieve the intended purpose.
China bucket mould basics
Most plastic products are formed by plastic moulds. According to the characteristics of moulding plastics, plastic moulds are divided into thermosetting and thermoplastic moulds.
By their very nature, bucket moulds must meet multiple demands simultaneously during the moulding process. In order to form a bucket with a cavity shape, the bucket mould must contain a polymer melt within the cavity. To create the injection moulded bucket, heat is transferred from the hot polymer melt to the cooled mould steel as uniform and inexpensive as possible. Finally, the bucket mould produces fairly repeatable part ejection, which makes subsequent moulding more efficient.
Among other requirements, China bucket moulds are expected to perform these three functions—containing the melt, transferring heat, and expelling the moulded bucket. In the case of containing a polymer melt in a bucket mould, the bucket mould must be made to resist enormous forces that could deflect or open the mould, and it must contain a feed system that directs the polymer melt from the moulding machine to one or more cavity in the bucket mould.
Additionally, these secondary functions may result in tertiary functions when specific bucket mould components or features are used to implement them. Bucket moulds perform many functions but should only be considered samples of the necessary primary and secondary functions during the design phase. Even so, skilled designers are aware of this when different functions place conflicting demands on bucket mould design. Multiple cooling lines closely spaced can provide efficient cooling by conforming to the cavity of the bucket mould.
When disassembling buckets, it may be necessary to use thimbles where cooling lines are not required. It is the responsibility of the bucket mould designer to design bucket moulds in a way that meets conflicting requirements. When in doubt, novice designers tend to overdesign. The tendency to do so often results in large, inefficient, and expensive China bucket moulds.
Parts of China bucket mould
China bucket mould generally consists of the following parts:
(a) Mould base
Generally, choose a standard mould base from standard mould base manufacturers.
(b) Mould inserts
Used for moulding plastic buckets, plastic mould factories generally produce these themselves; most of the processing time is spent on producing mould inserts.
(c) Die auxiliary parts
Including positioning ring, nozzle bushing, support column, top plate, guide sleeve, guide pin, lifting ring, etc.
(d) Four systems
Injection system (runner)
The term “injection system” refers to the portion of the runner, which includes the main runner, cold material, secondary runners, and gates, before the molten plastic enters the cavity from the nozzle. It is directly related to the quality and production efficiency of molded buckets.
Ejector system
Ejector pin, blade pin, and sleeve.
Heating and cooling system
Hot runner, preheating device, and cooling water.
Exhaust system
Exhaust groove, parting surface exhaust, thimble exhaust, blade exhaust;
Special mechanism: If the bucket has undercuts or sidewall holes, the plastic China bucket mould needs to design a side core-pulling mechanism, an inclined core-pulling mechanism, and an oil cylinder.
Classification of China bucket mould
1: 2-plate China bucket mould
Another name for gate mould, also known as single-parting line injection bucket mould. It is characterized by a simple mould structure, but the gate is a part of the injection moulded bucket and needs to be removed after manual operation. The plate bucket mould structure is widely used in various moulds.
2: Three-plate China bucket mould
Precision gate mould and double parting line injection mould. The gate characteristics are precise, and the gate section is small. The appearance of the injection moulded buckets is good, and there is no need to remove the gate in the later stage manually, which is conducive to automatic production. However, the structure of the three-plate mould is more complicated, and the cost is higher. Generally suitable for small and medium plastic buckets. Plastic moulding materials have good flow properties.
China bucket mould production tips
While the standards and techniques used to produce bucket moulds have changed dramatically in recent years, the basic rules for developing moulds that meet the original design standards and function effectively have not changed. These tips are based on many years of experience in bucket mould making in China. Many of these skills are related to communication. As any bucket mould maker will tell you, incomplete information is often available at the beginning of a project. It’s like having only half the map; the chances of getting to your final destination on time are very slim.
1. Design with specified cost and time criteria.
The old rules of “good, fast, inexpensive” still apply. After extremely short deadlines, there always seems to be time for rework or adjustments, but It’s best to provide adequate time for review and corrections during the design phase.
2. Make sure your design specifications can be produced using existing technology.
The availability of programs such as Solidworks and rapid prototyping can provide early insight into potential problems that may occur before metal cutting. Provide the engineering team with the complete specification and do not leave anything out. If something is missed here, it will cost time and money to fix later in the process.
3. Share your company’s design philosophy with us and allow our design team to contribute.
Many bucket mould manufacturers design new moulds and dies based on their current inventory and operating environment.
Production can be accelerated by making some very simple modifications to the design. Invite your paint bucket mould maker for suggestions that can improve formability.
4. Before manufacturing begins, establish clear guidelines on the minimum thin-walled barrel die life and capacity required.
Clearly defining a mould or die’s expected performance and service requirements can help save upfront money. If your product is likely to be modified or replaced relatively quickly, the mould maker’s engineering team can design accordingly.
5. Let the mould maker make a production schedule to allow a reasonable amount of time for bench testing before delivery.
In laboratory situations, moulds are often delivered without fine-tuning to meet production deadlines. Your mould maker should have the opportunity to run sample parts at his factory. If there is a problem, he can correct it before delivery.
6. Set up weekly progress report calls/emails with your sales reps during manufacturing.
Sales reps are busy people. It helps establish a common point of contact to ensure projects are on schedule and within budget. Regardless of the project size, it’s worth making weekly calls to eliminate assumptions.
7. Ask the mould maker for clear guidelines on maintaining thin-walled bucket moulds after installation.
Bucket moulds may operate in less-than-ideal conditions. Improper material storage, irregular mould cleaning, poorly maintained presses, and ill-trained operators can all contribute to poor mould performance. Your mould maker should provide care and maintenance instructions based on usage specifications.
8. During the initial start-up and trial period, a field sales representative from the mould shop was present.
Many moulds suffered severe damage due to poor installation and required immediate repair. Having a technical representative on site when the mould is first installed is good insurance.
9. Remember that designing and manufacturing a mould or die is a collaborative effort.
Science and art are combined in the creation of moulds. Building a tool that can work 24/7, if needed, requires careful planning and inspection at every stage of production. Allow your employees the time and expense to visit the mould shop facility during production.
10. Don’t cut corners!
It probably doesn’t make sense to give the job to the lowest bidder. Pay a reasonable price for a mould. If your budget is too low, you may be able to rebuild or repair thin wall barrel moulds in a relatively short period of time. Trying to squeeze every last dollar out of a china bucket mould maker estimates could end up doubling the cost of the project. Price is, after all, what you pay for the mould. Cost is what you continue to pay for a mould that was not built correctly in the first place.
Advantages of China bucket mould
1. It allows complex geometries with tight tolerances.
Bucket moulds allow for a large number of uniform, complex buckets. You should pay attention to vent and gate locations, corner transitions, wall thickness, rib and boss design, etc., to simplify ejection and obtain accurate buckets.
With bucket moulds, you can easily achieve repeatable bucket tolerances of ± 0.500 mm (0.020”). In some cases, you can even produce buckets to a tolerance of ± 0.125 mm (0.005 in), giving you accurate enough buckets for most applications.
2. Compatible with a variety of materials and colours.
Today, more than 25,000 engineered materials are compatible with injection bucket moulds, including thermoplastics, thermosets, resins, and silicones. With all these options, you will be able to find an option that achieves the right balance between physical, mechanical, and chemical properties. Commonly used materials are acrylonitrile butadiene styrene (ABS), polyethylene (PE), polystyrene (PS), polypropylene (PP), and so on. You can also use mixed materials to produce buckets with the required strength, impact resistance, or stiffness. For example, you can add fiberglass to thermoplastics to make composites with increased strength.
When it comes to colors, you also have a variety of options. To create your desired color, think about employing masterbatches, pre-colored resins, liquid colourants, or salt and pepper combinations.
3. High efficiency.
While 3D printing or CNC machining a single bucket can take minutes or even hours. Cycle times for injection bucket moulds are typically between 10 to 60 seconds, even if the moulding process for a complex geometry takes 120 seconds. This helps maximize efficiency and get the most out of each bucket mould, allowing you to manufacture hundreds of identical buckets per hour at a low cost.
4. It provides high repeatability and reliability.
One of the main advantages of plastic bucket moulds is its high repeatability. Once the bucket mould is created, you can produce thousands of buckets before you need to maintain the tooling. An aluminium bucket mould typically uses 5,000 to 10,000 cycles, while a full-size steel production bucket mould can use over 100,000 cycles. Plus, you’ll have the same product since injection bucket moulding uses the same mould for each part.
5. You can reuse materials.
Although injection bucket moulding produces less post-material waste than many other manufacturing processes, it still produces excessive amounts of scrap. However, you can easily regrind, melt and reuse any gates, runners, or other leftover plastic parts to save material and reduce material waste.
China bucket moulds with YuanCheng mould
Between its efficiency and high repeatability, YuanCheng bucket moulds have many advantages. However, it’s easy to make a costly mistake that delays production for weeks. That’s where a trusted manufacturing partner can help.
When you work with YuanCheng mould, our team of experts can guide you through the production process and answer any questions about the advantages and disadvantages of China bucket moulds. Ready to get started? Contact us today.
