Bottle cap mould

Bottle cap mould| The ultimate faq guide

Introduction

Bottle caps are unavoidable parts of our daily lives. Bottle cap moulds are significant in water bottles, drug containers, and diverse sectors. Knowing the manufacturing details of different bottle caps is a top priority to enjoy the optimum performance and excellence of plastic cap moulds.

This FAQ guide will inform you of the ins and outs of versatile moulding processes. Let’s make a move.

How are plastic bottle caps made?

Plastic bottle caps are obligatory components to protect the substances inside a bottle. The bottle cap mould functions like an enclosure for containers. Some specific techniques must be followed during the production of bottle caps.

Usually, plastic bottle caps are made through injection moulding production and the production moulding production methods. In both ways, several plastic materials like HDPE, LDPE, etc are supremely effective.

The production procedure starts with sucking the combination of plastic materials into bottle cap injection molding machine’s barrel. Then, you have to heat the barrel until the material’s mixture turns into a medium-melt plastic phase.

Figure 1 Plastic bottle cap mould

After heating is completed, it is placed in the mould’s hole. Then, it needs to be cool enough to take the cavity shape. In the last segment, it is required to de-mould it. After the cutting and padding process, you will get the desired plastic bottle caps.

This is the basic method for plastic bottle mould. You can find some slight differences in this making concerning the moulding process.

What types of plastics are used to produce bottle caps?

Plastics are the most common materials in plastic cap moulds. Though plastics have numerous categories, reusable plastics are worthwhile for the production of bottle caps. When choosing plastics, you need to consider some factors.

Robustness is a vital issue for cap moulds. Plastic materials having sufficient resistance against external forces are preferable. This increases the longevity of bottle caps. For example, water container caps are comparatively less robust than prescription bottle caps.

The physical state of the content inside a bottle is also important. The use of plastics in cap moulds should be different for powder or liquid substances.

Considering the factors mentioned above, we recommend you the following plastics are widely used in bottle cap mould.

HDPE

This is high-density polyethene produced through the polymerization reaction of ethene at around 200 atm pressure and 200-300⁰C temperature. This plastic keeps the internal bondings of bottle caps compact. Again, HDPE plastics reduce the bottle cap’s weight significantly.

Figure 2 HDPE materials for bottle cap mount

LDPE

It is the short form of low-density polyethylene. It provides impressive protection against mechanical stress and improves the flexibility of bottle moulds.

PET

Polyethene terephthalate (PET) is widely used in soft drink bottle caps. These plastics are delicate and mechanically durable.

PP

Polypropene is found in most cap moulds. It ensures tight and rough characteristics in the container’s lid.

What is the process for making a plastic cap mould?

The production process of plastic bottle cap mould can be classified primarily into injection and continuous compression processes. You can effectively manufacture plastic container lids through these mechanisms.

Multiple caps can be produced from a single injection moulding. In injection moulding, thermoplastic materials are heated to a certain level so that the colour can be easily customized. The polymers become flexible in this thermal state.

Next, the manufacturer injects these soft thermoplastics into a steel mould, which transforms the polymer’s shape according to the size of the bottle caps. The remaining part is separating the bottle caps after opening the mould.

Figure 3 Plastic cap molding Process

On the contrary, the manufacturer applies a lesser amount of pressure and temperature for continuous compression moulding. This process is easier because of using resins. When the extrusion completes, soft plastics are placed in a cavity.

Then, the top and bottom moulds get closed to compress the heated thermoplastic polymers. The rest of the process which includes cooling, cutting, washing, etc is similar to injection moulding.

What is the embossing of hard plastic in manufacturing?

The embossing of hard plastic in bottle moulds deals with adding any writing or logo. Usually, the manufacturer applies an embossed company logo and the key message.

Proper embossing reduces the use of labeling and is useful from a promotional perspective. Consumers sometimes miss the labels on plastic containers, but the embossing with customized color is easily noticeable when opening the caps.

Besides, it does not add extra expense to your production cost. The most noteworthy fact about embossing is that it lasts for a long period compared to labelling. That’s why you should consider this when manufacturing bottle moulds.

What moulding methods are used in plastic cap mould?

There are two major types of bottle cap mould. Let’s have a look at the prominent features of these moulding processes.

Compression bottle cap mould

• Its appearance is impressive due to the absence of a pouring point.
• This bottle cap mould can be processed at a low temperature.
• You can replace the compression moulding cavity individually because of its independent feature.
• Its printing effect is superior to other bottle moulds processes.
• The depreciation rate is low in this case.
• You just need to supply a temperature of around 170⁰C to heat the plastic materials to reach their molten flow phase, which is why this process consumes little energy.
• Its extrusion pressure is relatively low.
• Compression moulding consists of cover size having higher accuracy.

Injection plastic bottle cap mould

• The energy consumption rate is higher in this case.
• Here, the required temperature for melting the materials is around 220⁰.
• Injection moulding is a high-volume process. So, you can’t replace its cavity easily.
• This process requires a higher temperature and extrusion pressure than the compression moulding.
• The shrinkage of bottle caps is high
•  Its cover size, appearance, and printing are good enough for bottle moulds.

So, you can understand that both of these mould methods have immense applications in plastic bottle caps manufacturing.

What is the injection moulding process for cap mould?

Injection moulding is a widely-used effective way for plastic cap mould. This process consists of the following steps.

Plasticization

This process refers to heating and melting the plastic materials at a specific temperature.

Injection

Molten plastics are injected into the mould cavity along with the advancement of the screw of the plastic cap injection molding machine.

Figure 4_ Injection Moulding For Washing Bottle Caps

Cooling

Now, melted polymers are cooled for a certain time to harden them. The cooling time depends on the bottle cap’s dimensions and resin temperatures.

Ejection

At this stage, an ejector removes the mould pins, and then the mould is removed.

Packaging

This is the last part. Here, the operator separates the parts from the runner and starts packaging.

The Future Of Plastic Cap Molding: Innovations And Sustainability

What are the advantages of compression moulding for plastic cap mould?

Compression bottle moulds have numerous technical advantages that promote plastic bottle caps’ performance. Its most noteworthy benefits are explained here for your convenience.

Low energy consumption

The required temperature to plasticize the materials in compression moulding is low (around 170⁰C), so the energy consumption rate during the heating and cooling process is low.

Appearance

Compression moulding ensures the impressive external appearance of bottle caps. It has become possible because there is no pouring point here.

Figure 5_ CCM Bottle Cap Molding

Short cycle period

This process enables fast cooling and demolding due to lesser pressure and temperature requirements. That’s why its cycle time is short which leads to higher capacity.

Ecologically effective

Compression molding minimizes the distance between the temper band and the bottle cap body. Thus, it produces less pollution and becomes an eco-friendly bottle cap mould method.

Low material waste

Since the hot runner is not involved, plastic material wastage is considerably low here. This is around 5-10 kg in color changeover.

Easy replacement

Its low-volume characteristics make the mould cavity separate. So, its replacement is very simple.

Consistency

Bottle cap mould with compression moulding is less vulnerable to shrinkage effects. This property promotes the dimensional stability of bottle caps.

What kind of machinery does the plastic bottle cap have in addition to the injection moulding machine?

In addition to the injection moulding machines, plastic bottle caps have compression moulding machines. These plastic cap injection molding machines have different types based on their number of cavities, productivity, diameter, etc.

Figure 6 Plastic cap injection molding machine

Such as CCM ( continuous compression machine) 48 has the following features:

• 48 mould cavities
• Maximum productivity is around 2000 closures per minute
•  The highest diameter of the closure is 38mm.

What are the differences between the compression moulding production process and the injection moulding production process?

Compression moulding provides a better experience during the production of bottle cap mould than injection moulding in many aspects. Here, a comparison between these two processes is given that will help you to choose the best process for bottle cap mould.

• Compression moulding consumes less energy. Here, thermoplastic polymers are heated to around 170⁰C. On the contrary, the injection moulding process uses more than 220⁰C, which results in higher power consumption.
• The replacement of compression moulding is easier than injection moulding.
• The injection molding can’t deliver the optimum printing effect like the compression bottle cap mold.
• The produced shrinkage is lower in the case of continuous compression moulding. This property leads to a short cycle time for plastic bottle mold.
• The injection process during the production of bottle caps is a little bit complicated because of its high-volume nature.
• Bottle cap mould looks better in the case of compression moulding.
• You can achieve better durability for the bottle caps when you apply injection moulding production process.
• Injection moulding is effective for complicated shapes of bottle caps at an affordable rate.

Figure 7_ Plastic Bottle Caps Compression Moulding

These are the distinguishing factors between the two production methods. You should choose the one that is suitable for your requirements and production level.

Which variables affect the cost of injection moulding?

Injection moulding is a cost-effective process to manufacture plastic bottle caps. Since cost influences your choice to a large extent, you need to consider the factors that affect the manufacturing cost through this method. We are here to inform you of the cost variables.

Mould design

The shape and design of injection-molding bottle caps influence the production cost. A complicated mould size requires excessive care and cost.

Materials

Injection moulding cost depends greatly on the material selection. If you choose materials with low efficiency and durability and a long production cycle, you can’t ensure cost minimization.

Thermoplastic polymers with variable density can serve for a long period. That’s why these materials are cost-effective despite their high cost.

Aluminum can also be used due to its low initial cost. However, its low longevity does not support the expected cost.

Pressure & temperature

High pressure and temperature increase energy wasting. That results in a high production cost for injection molding.

Mould cavity

A bottle cap mould with Multiple injection moulding cavities effectively minimizes the cost for high-volume productions. Though it is primarily expensive, its worthwhile productivity trades off this effect efficiently.

But, you can think about a single mould cavity for small-scale bottle caps manufacturing.

Mould base

The mould base is a necessary segment of the injection moulding process. It contains the cavity and components. Its size and materials also significantly affect the production cost. Moreover, the cost will increase in the case of a customized mould base.

As you are aware of the variables that affect the cost, you should know your dos and don’ts. You need to choose long-lasting and effective materials and eliminate avoidable features of bottle cap mould.

How to control the mould temperature in plastic injection moulds?

The mould temperature control in plastic injection moulding depends mainly on the temperature control unit, heating-cooling channel, coolant, etc. To achieve maximum control over the mold temperature, you must meet the following criteria.

• The diameter of the heating-cooling channel should be large to handle high pressure and ensure a stable flow through it.
• The inlet and outlet temperature of the coolant should be slightly different.
• Thermal conduction of the coolant needs to be optimum.
• There should be sufficient heating-cooling channels in the bottle cap injection molding machine.

Figure 8_ Temperature Controlled Injection Moulding

In plastic cap mould design, which factors should be considered for maintaining proper cap dimensions?

Dimensional accuracy plays a significant role in bottle cap moulding, whether it is compression or injection moulding. In that case, it is important to identify the factors that affect the cap dimensions.

Cooling time

You need to consider the cooling temperature to maintain proper cap dimensions. However, it depends on the cap’s density and cooling time. Decreased cooling time increases the cooling velocity, lessening the injection molding bottle cap closure’s density.

The dimensions of density and container lids are related reciprocally. So, the dimension ultimately increases due to low cooling time. Cooling temperature lessens linearly with the increase in cooling time.

Figure 9_ Oil Bottle Cap Mould

If it remains constant, cooling effectiveness becomes higher for molding than the de-molding process. That’s why the effect of cooling time can’t be ignored during the bottle cap mould design.

Mould temperature

The mould temperature is dependent on the resin temperature in the bottle cap mould. If the cooling time is not changed, the mould temperature will rise significantly, reducing the volume and dimensions of the bottle caps.

Masterbatch

It also influences the dimensions of the bottle cap die. It is very common to notice that the green closure has larger dimensions than the orange caps.

Cap’s weight

If the cap’s density remains the same, its weight and volume are proportional. That means the increase in the closure’s weight makes the dimension bigger. But, the scenario becomes different sometimes in practical cases.

So, the effect of the bottle cap’s weight is not always linear. It depends on the temperature change and the amount of weight.

Resin temperature 

It changes the thermal state of moulds and extruders. With constant cooling time, the bottle cap’s volume decreases due to the rise of resin temperature.

Except for these factors, the dimensional stability of injection-molding bottle caps moulds affects thermal conduction, materials, additives, etc.

How to maintain the quality of bottle cap mould?

Top-quality bottle cap mould is mandatory for ensuring the best performance of plastic bottle caps. So, you need to maintain the quality of moulding properly. The following measures are notably important to ensure high-quality injection molding bottle caps mould.

Mould dimension

Dimensional stability affects the quality of the bottle cap mould. That’s why you should avoid issues that change the bottle cap’s dimension. Proper maintenance of the dimension and volume ensures consistency in quality.

Working condition

Extreme temperature and pressure are not suitable for the quality maintenance of injection-molding bottle caps. So, you need to ensure a good working condition in injection and compression molding.

Figure 10_ High-quality Bottle Cap Mould

Inspection

Regular inspection prevents bottle cap quality from deteriorating. It is worthwhile to test the functionality, thermal conduction, durability, etc., from time to time.

Lubrication

Sometimes, injection moulding machinery gets stuck due to mechanical complications, resulting in low-quality bottle caps. Lubrication and oiling are effective ways to avoid such issues.

Downtime reduction

In this case, the downtime or stop time of moulding needs to be short. Long downtime promotes the quality degradation of bottle cap dies.

So, you can efficiently maintain the closure’s quality by following these measures.

How can quick color changeover in bottle caps production be achieved?

Color changeover is a vital issue in manufacturing bottle caps. This factor increases the production cost in injection molding bottle caps, so you need to achieve a quick color changeover in bottle cap production.

Process selection

The extrusion pressure is low at compression moulding. So, the melted plastics reach the nozzle quickly and mould after a thorough extrusion. This property makes the color changeover quick and easy.

Besides, recycled materials never block the pin in continuous compression moulding, which is present in the injection moulding process.

Figure 11_ Bottle Cap Mould Colors

Color arrangement

It is required to place the bottle caps from light to deep color arrangement. It reduces the time for the color changeover.

Time management

You can easily increase the color changeover rate by maintaining the time in a production cycle. First, you need to separate the different segments of recycled materials.

Thus you have a great chance of placing the materials of new color after completing the previous materials batch. In this case, you should keep an eye on the hopper window carefully to look after the color changeover.

Cleaning the hopper and discharging the waste in due time also ensures a quick color changeover in pet bottle die manufacturers. Verifying the compression moulding machinery is important to maintain consistency of production.

Skilled manufacturer 

Last but not least, choosing the right manufacturer with skilled technicians is important. They can operate the moulding equipment efficiently to continue production and lessen the time wasted in color changeover.

What are the features of 3 and 5-gallon water bottle cap moulds?

3 and 5-gallon water bottle die moulds are very common choices at present. Both of these water bottle caps have superior features. Such as:

• S136 steel for the mould cavity and mould base.
• The hardness of mould steel varies from 45 to 52
• The number of cavities is 12 or 16.
• The principal material is low-density polypropylene
• High mechanical endurance
• Glossy appearance
• Thermal resistivity is high
• Impressive fluidity
• Reliable cooling mechanism
• Long shelf life
• Numerous categories like non-spill water bottle caps, peel-of dust protection seal-incorporated bottle caps, etc.

What are the features of plastic bottle measuring cap mould?

Plastic bottle measuring cap moulds offer versatile, effective features that continuously increase their demand in the market. Plastic measuring caps are mainly composed of HDPE and polypropylene.

These polymers provide tremendous robustness and functional ability. You can use a plastic bottle measuring cap mould in extremely humid or cold situations. It keeps the liquid inside with great effectiveness and a good appearance.

Figure 12_ Plastic Bottle Measuring Cap

This bottle die is compatible with numerous shapes and designs. It has the endurance to a certain level of mechanical and chemical stresses.

What are the features of cosmetic bottle caps mould?

The importance of bottle dies in the cosmetic industry is beyond question. They ensure supreme functionality and aesthetic value, which promotes the product’s acceptance by consumers.

The most notable features of cosmetic bottle cap mould are-

• Usually, cosmetic bottle caps consist of PP (Polypropylene), PETG (Polyethylene Terephthalate Glycol), acrylic-reinforced resin, and HDPE.
• Impressive chemical endurance against toxic compounds
• High dimensional stability
• Moisture-resistant
• Great appearance
• Compatible with embossed design
• Low thermal expansion

To experience a premium feel in a cosmetic bottle cap mould, you need to choose the best materials and design.

How To Choose A pet Bottle Die Manufacturer in China?

Bottle cap moulds maintain the integrity of the content stored in a bottle. Numerous compression and injection pet bottle die manufacturers are in China, so choosing the right manufacturer of bottle caps should be a brainstorming task.

If you are firmly sure about your requirements, we have a guideline for making a good choice.

Manufacturing experience

A reliable bottle cap mould maker should have long experience delivering quality manufacturing service. The consumer’s review and working history can give you an idea about this.

Materials availability

Material selection has an immense influence on the performance of bottle caps. That means you need to choose plastic bottle cap mould manufacturers which have sufficient storage of effective and long-lasting materials.

Technical support

This is a vital factor in this case. A top-class maker must provide skilled technicians to operate the moulding processes. Otherwise, defect operations greatly increase the production cost.

Moreover, professional technical staff can deliver one-stop customization. It is highly effective for getting the bottle cap mould according to your desired shape, colour, etc. Besides, smart technical support is necessary to conduct performance testing.

It ensures hassle-free assembly, internal structure, surface treatment, mould resistance, etc.

Customer care service

24/7 customer service shows the maker’s care about the product and consumers. So, you have to check this feature while choosing a bottle cap manufacturer.

Equipment facility

An elite bottle cap maker must provide the necessary equipment for smooth and flawless moulding. The following machinery is required for the production process of both injection and compression moulding.

• Mirror spark machine
• Computer numerically controlled (CNC) milling machine
• Numerical controlled lathes
• 3D equipment for functional test
• Grinders
• Measuring equipment
• Cutting instruments

These types of equipment are worthwhile for the quality control and trustworthy inspections of cap mould.

Conclusion 

This is evident from the supremacy of bottle caps in material protection. Effective moulding technologies ensure perfection in their manufacturing.

We hope this FAQ guide, with a straightforward explanation, will make you an expert in bottle cap mold.

Stay tuned.