Plastic injection molding company workshop China

The importance of injection mold maintenance

Mold maintenance, or tool maintenance, refers to the cleaning and repairs that are needed to keep an injection mold in the best working order. Maintenance is performed routinely over the life of the mold, and also when any problems arise.Mold maintenance is crucial because it affects the quality of the plastic component as well as a company’s bottom line.

The condition of the injection mold affects the quality of the plastic components produced. Your molds and tools are critical assets to your company, yet many buyers overlook mold maintenance when making sourcing decisions. In fact, how your supplier maintains your molds is a critical aspect of a successful long-term business relationship.

What problems does mold neglect cause?

Injection molds undergo a lot of stress in the course of carrying out the molding process. Depending on the design of your mold, factors like temperature fluctuations, opening and closing of the mold, ejector pin action, and other movements can all cause natural wear and tear on a mold. A good injection mold will be designed to handle this wear and tear, but unpredictable situations can still arise as a result of these numerous stresses and the nearly innumerable permutations in which they can interact.

Temperature fluctuations, for instance, can cause both internal and external stress on the mold. Especially if the mold is not designed in such a way as to allow for more uniform cooling, molds can expand and contract in response to heating and cooling, and can weaken from the stress — and potentially even crack.

The moving parts of the mold are susceptible to friction, rough points of contact, and mechanical breakdown. A mold that doesn’t open and close smoothly, for instance, may be subject to impact stress as the two halves meet each other. Ejector pins may not function properly after a certain number of molding cycles. What’s more, the friction of the moving parts, in addition to creating extra heat, may eventually wear away at critical parts of the mold, creating unintended cavity shapes or compromised contact points.

Aside from the aspects inherent to the mold itself, there are also maintenance issues related to the material injected into the mold. As the mold completes more and more cycles, minute amounts of material residue can begin to collect inside the mold cavities. Over time, these deposits can accumulate and affect the interior shape of the cavity — and thus, the shape of the finished part. Deposits in mold runners or the mold cavity can also affect cycle time and, left unchecked, can even begin to prevent the substrate from reaching areas of the mold.

If a mold is used with different materials, these deposits might also create unintended interactions, depending on the chemical makeup of those materials. This, in turn, can affect the structural integrity of the finished product.

What does injection mold maintenance involve? 

The most important part of mold maintenance is creating a maintenance schedule and sticking to it tightly. Molds must be maintained regularly if their lifespan is to be prolonged. Ideally, manufacturers should perform cleanings, inspections and maintenance on molds after they have undergone a set number of cycles. However,Setting the schedule can be tricky, because different molds age at different rates, conditions wearing them out differ from manufacturer to manufacturer.  

One way to begin figuring out how often a facility should perform maintenance on each type of mold is to keep a log of all mold maintenance and repairs that become necessary. Be sure to keep track of the data and information you collect in a centralized log for easy reference.Knowing how often a given type of mold will break down without maintenance can help factories determine how often it needs to be inspected. The manufacturers of the injection mold will also be able to provide information on how often the mold will likely need maintenance. Advice from manufacturers will of course be more helpful if they have adequate information about the environment in which the mold will be used.

Regular mold maintenance and cleaning can improve shot quality, as molds will be in a more uniform state of cleanliness and wear and thus produce more uniform results. The most important factor in making sure molds are always in good condition is the regularity of maintenance, it is also essential that the right kind of maintenance is performed. It is especially important to pay attention to hot runners and water lines, as they often cause mold performance problems. Mold maintenance should also of course include lubrication, cleaning and tightening of all parts. Finally, rust prevention sprays must be applied to a cool, dry mold if they are to work.

Working with a reliable injection mold supplier as a strategic partner can help reduce many of the risks and costs. Jingwei industry has served the injection molding industry for over 15 years and has a team dedicated to providing you with the most cost effective solutions for design and manufacturing injection mold.Please visit us at :jweimolding.com or contact us via info@jweimolding.com.

Choosing the Right Material for Injection Mold Tooling

With many different types of mold material options available(Hardened steel,Pre-hard Steel,Aluminum) ,all formulated to meet specific requirements, ensuring the material used to produce your injection mold has a positive impact on the success of your next project. Similar to plastic resins being formulated to meet performance criteria in various applications, steel is also alloyed to meet specific requirements.Choosing the proper material for your next plastic injection mold can often be as critical as choosing the right plastic resin for your part.

Circumstances that effect choosing the proper injection mold material include:

• ensuring parting line integrity;
• wear resistance because of mechanical fatigue;
• wear resistance because of abrasive or corrosive plastic resins;
• inclusion of thermal properties needed to successfully mold your plastic part.
  

The most common materials used to construct plastic injection molds are pre-hard steel, hardened steel, and aluminum. This 3-part series will explore each and answer the important questions you should consider before choosing your material:

1,How many parts are expected to be molded?

Pre-hard Steel: Typically found with a Rockwell rating of RC 30-42 (in its pre-hardened state), this material is quite tough, easy to machine and relatively inexpensive. 250,000-500,000 cycles can easily be achieved when molding unfilled materials, and 50,000-100,000 cycles can be obtained with filled materials. The range is dependent on the amount of filler present in the plastic material. When total expected volume is less than 250,000 cycle’s, pre-hard steel is the way to go.
Hardened steel:Typically found with a Rockwell rating of RC 46-62 , it can be a great material for creating core and cavity detail. With hardened steel molds, one can easily achieve 1,000,000 cycles for unfilled materials and 250,000-500,000 cycles with filled materials. Once again, this range is dependent on the amount of filler present in the plastic material.
Aluminum: Generally speaking, aluminum molds are used in lower volume productions, not exceeding a few thousand parts.

2,What surface finish requirements are expected of the molded part?

Pre-hard Steel: This may include light to aggressive textures, EDM finishes or polish. An A-1 or better polish can be achieved but this is grade specific.
Hardened steel:As long as your requirements do not exceed that of an A-3 requirement, pre-hard steel is a great choice.
Aluminum: Most grades of aluminum machine, finish and accept texture proficiently. Most high-end aluminums have the ability to accept a polished surface, often ranging between a B-1 and A-3 polish.

3,What steel conditions exist as a result of the part design and are they conducive of excess wear?

Hardened steel: With hardened steels you can decrease the amount of draft of wiping shut-offs to about 3 degrees.
Pre-hard Steel:pre-hard steel has fair compression strength. Because of this, pre-hard steel is a great candidate for lower volume production tooling, including insert molding and overmolding.
Aluminum:Aluminum has very poor compression strength. If you happen to close the mold on a single part or insert, the aluminum will “hob” and become damaged, requiring expensive repair. For these reasons, aluminum is not well suited for any type of insert or over molding.

4,What type of plastic resin will be used on the molded part?

Pre-hard Steel:If molding highly corrosive molded resins, like PVC, common metals can quickly corrode, so 420SS is highly recommended. There are many options that offer different levels of hardness, as well as corrosion resistance.
Hardened steel:High heat resins such as PEI, PPS, PPSU, PPA, and PEEK, as well as filled materials (long and short glass fiber, carbon, stainless steel, etc.), can often be tough on pre-hard steels from a wear perspective. While certain steps can be taken, like inserting the gate area for easy maintenance and replacement, it should be expected that the life of the mold will decrease in these circumstances. If you find that your project requires between 50,000-100,000 parts over the life of your program, pre-hard steel is certainly adequate.
Aluminum:Aluminum is very vulnerable to fast wear and fatigue when high heat or highly abrasive materials are being molded, and should not be considered for any type of production molding. However, it can still be a great choice for extreme low volume (truly prototype) and non-cosmetic parts, even when running such materials.

By considering these 4 basic questions, you can make a more educated choice as to what the correct material is for you. While choosing the best option for your mold is not complicated once you understand the pros and cons of each material, it is a critical part of the process that can affect the success of your project. Research done prior to mold construction, and more importantly vendor selection, can help ensure you receive the performance you expect from your next mold.Jingwei industry has served the injection molding industry for over 20 years and has a team dedicated to providing you with the most cost effective solutions for design and manufacturing injection mold.Please visit us at :jweimolding.com or contact us viainfo@jweimolding.com.

Basics of Plastic Injecion Molded Parts Production

Creating a plastic part using injection molds requires three important components:The mold;An injection molding machine;Raw plastic.Making a basic plastic part is relatively simple if you have the right tools. Knowing what is needed can help you understand how your requirements will be met, and you can more easily communicate your needs to a plastic injection mold manufacturer.
Consider the size of the final part when you determine which machine to use. The more complex your design, the more features you are likely to need to consider. This ensures that you are able to select the right raw material and machine to complete your injection molded parts.
The strength and durability of the final product depends on which raw material you select for your injection molds. Molds for plastics come in many different shapes and sizes, and the success of your final product starts with the raw material.
The plastic mold itself is typically something you will have to develop. Experts can help you interpret your needs and design the right type of plastic mold for each unique project.
Before launching your next plastic mold project, remember these simple steps. Although the manufacturing process is straightforward, you need the right expertise for a high quality, on-time, cost effective finished product.Jingwei industry has served the injection molding industry for over 20 years and has a team dedicated to providing you with the most cost effective solutions for design and manufacturing.Please visit us at :jweimolding.com or contact us via info@jweimolding.com.

How to Optimize Your Plastic Injection Mold Designs

Designing better parts initially will help ensure a smoother transition to production and faster delivery of your new products.A lot of time and attention goes into making a successful plastic injection mold design. If you don’t get the design right, nothing you do is going to compensate for that later. Here are a few simple guidelines to help you get the right design from the beginning:

• Size of the mold:The maximum part outline that can be molded is approximately 18.9 in. (480mm) by 29.6 in. (751mm) or roughly equivalent to 175 sq. in. (1,129 sq. cm.). A maximum part volume of approximately 59 cu. in. Depth up to 4 in. (101mm) from the parting line with 3 degrees of draft, or up to 8 in. (202mm) total if the parting line can pass through the middle of the part, inside and outside. Deeper parts are limited to a smaller outline
• Tolerances:Typically,Jingwei industry can maintain a machining tolerance of ±.003 in. (0.08mm) with an included resin tolerance that can be greater than but no less than ±.002 in./in. (0.002mm/mm).
• Wall Thickness :With injection-molded parts, observing proper wall thickness helps parts avoid potential issues such as sink marks and warpage.
• Drafts :Drafts  are actually vital to ensuring that you have taken all of the other aspects into account and have worked to improve the mold based on any new information. Drafts give you a way of seeing where you have been and what did not work before or highlight areas where you think previous design versions were better.

Every mold design needs to take above four primary factors into account before being made.Size,Tolerances,Wall thickness should be located on the specifications or requirements for the mold. If you do not have these, that should be the first step in the process because these three factors tend to be the reason that a mold either succeeds or fails.

• Surface finish:Surface finishes play a critical role in both functionality as well as the cosmetic look and feel. Parts that are hidden may not require a surface finish at all;
• Undercuts:An injection mold undercut is any indentation or protrusion that prohibits an ejection of a part from a one-piece mold.Reducing the number of undercuts often helps to reduce the initial cost of tooling.Undercuts are critical on things like bottle caps, but not all molds will require undercuts as part of the plastic injection mold design.

Jingwei industry has served the injection molding for over 15 years and has a team dedicated to providing you with the most cost effective solutions for design and manufacturing your new products.To know more,Please visit us at :jweimolding.com or via info@jweimolding.com.

Things About Injection Molds Your Boss Wants To Know

Injection molds are one of the reasons why mass production has become so popular, and why so many manufacturers rely on custom mold makers to produce the perfect mold. Here are things that you may not know about injection molds.

1. Injection molding can be fully automated and thus permits very high rates of production (you can mass-produce parts very effectively through injection molding processes).
2. Injection molding allows for the production of highly detailed and intricately designed parts. You will need an engineering design firm or an in-house department to make credible designs, however, once the part is ready for and produced via injection molding,Custom mold makers have perfected the process well enough that final products can have fine details and incredibly intricate designs to meet very strict requirements.
3. Custom injection molds are often cheaper and more durable than 3D printed molds because the amount of time required to make a complete part is usually in the cooling process.
4. You can use a variety of materials in injection molding as well as combine different materials to synthesize desirable material properties in your final product. The combination of more than one injection molded material  is known as co-injection molding.
5. Injection mold makers can actually use aluminum in the products. It is not a common material, but can be used alongside the more common plastic injection molds. This addition will help when a higher heat tolerance is required.
6. It is rare that a mold is perfect the first time, even with a production mold. so if you work with a tool maker who gives you an 8 week delivery on the tool, be aware that that does not necessarily mean that your part will be useable in 8 weeks.Experts are required to ensure that the final product meets your needs. They can test and measure the mold and first round of injections to see if there is a problem and determine the best way to fix it.
7. Mold inserts can be used to make new parts so that you do not have to recreate a similar insert for different projects. It is a matter of changing the internal cavity instead of redesigning and machining the mold.

Jingwei industry has served the injection molding industry for over 15 years and has a team dedicated to providing you with the most cost effective solutions for design and manufacturing your new products.To know more,Please visit us at :jweimolding.com or via info@jweimolding.com.

4 Steps to Achieve Proper Tolerance for Superior Product Performance in plastic injection molding

Tolerance is an acceptable limit of variation in a physical property or dimension.Defining a tolerance will identify boundaries for acceptable variations that will not affect the function of a part or system.
With the injection molded process, major factors that impact tight tolerance include part design and complexity, material selection, tooling, and process design and control. They can make it difficult to hold dimensions to the exact value. That is why an acceptable tolerance is necessary.
If tolerance is not done correctly, parts and products will underperform or possibly fail, resulting in customer dissatisfaction and a tooling and/or process overhaul，delays in production and unexpected additional costs. Below are 4 aspects that play key roles in aligning proper tolerance for superior performance.

1. Part Design and Complexity

The first step to controlling tolerance is to establish the tolerance zone during the design phase. Designing the part is the biggest factor in controlling tolerances. Making improvements during the design phase will not only achieve repeatable tight tolerances, but also improve manufacturability, quality, and customer satisfaction, all while reducing costs.

• Shrink rates can vary depending on the material selection and product wall thickness. Thicker sections may shrink at a different rate than thinner sections. Varying shrink rates can affect the ability to hold tight tolerances.
• Part size can affect shrink rates as well. Small components have smaller shrinkage and are easier to maintain tighter dimensional control. However, large parts can be challenging to hold tighter tolerance as they shrink over a greater distance.
• Analyzing mold flow before production can be beneficial. Accurately predicting gate location, fill speed, shear stress, packing, cooling and shrinkage will help define the tolerance zone.
• Avoid tight tolerance in areas that are prone to warp, shrinkage or distortion.

2. Material Selection

Material selection is another decision that must be made early in the design process. Different resins can produce different tolerances for the same part, so sometimes a tradeoff must be made between tolerance expectations and the physical properties of the resin.

• A components environment can affect plastic properties and can result in a deviation from the tolerance. Plastics have larger thermal expansion than many other materials. Testing and measuring tolerance along with thermal expansion and part shrinkage in the components normal operating environment is crucial to controlling tolerance, but most importantly tight tolerance. Climate-controlled environments hold tighter tolerances well. On the other hand, tight tolerances are not always necessary in environments where temperatures are uncontrollable or where plastic expansion or contraction occurs.
• As mentioned in the design phase, shrinkage can affect tolerances. Part geometry can cause different shrink rates. Different resins also have different shrink rates. It is important to know resin properties in combination with part complexity to understand shrink rates to align proper tolerance zones.

3. Tooling

Tool design, tool material, and cavitation all impact tolerance. The need to heat and cool tools, and the number of cavities in the mold, can make holding tolerances more of a challenge. If tooling is not designed to provide consistent, repeatable cooling, shrink rates will vary and tolerances will be harder to achieve.

• Complex parts require complex tools. As a tool becomes more complex and additional components and features are added, it is important to make sure all components are transferring heat properly, allowing for acceptable resin and part cooling.
• Monitoring pressure will identify resin viscosity, fill time and many other production processes that can affect resin properties and result in deviations and application failures. Utilizing in-mold pressure sensors will help track the proper pressure at each stage of the molding process.
• Identifying an adequate gate location is important to achieve optimal material flow. This will contribute to avoiding unexpected shrinkage and warping.

4. Process Design and Control

Setting up the ideal process for the part, and being able to repeat it, is the key to molding tight tolerance parts. Proper process and document control from the beginning of production will ensure the component does not experience unnecessary pressure, stress, heat, or additional factors that can disrupt resin properties or application function.

• Many parameters and variables must be carefully controlled during injection molding to achieve tight tolerances. Proper process control and process development ensure the part does not experience unnecessary pressure or stress during the molding process. Matching pressure curves versus simply using machine parameters such as time, temperature, and pressure help eliminate the lot-to-lot variation that is common in the industry. Conducting injection-molding operations in a climate-controlled facility also reduces process variation.
• Understanding end user intent, life cycle expectations and environmental encounters are important to share and discuss with your plastic manufacturing partners. Keeping lines of communication open with your plastic manufacturer will aid the success of your application.
• Repeatable processes can be achieved by conducting a Rheology test and a gate test. These tests will show you how repeatable your process and machines are, as well as, aid the optimization of your process and cycle time.

Jingwei industry has served the injection molding industry for over 15 years and has a team dedicated to providing you with the most cost effective solutions for design and manufacturing your new products.To know more,Please visit us at :jweimolding.com or via info@jweimolding.com.