Selecting the best plastic mold manufacturer from the start is crucial
The most crucial and challenging part of any plastic injection molding project is the mold building. It requires a lot of time and money, and it does not allow for trial and error. That is why you need to select the right mold manufacturer from the start, or else you will face a lot of difficulties and expenses if you switch suppliers later.
What pitfalls you need to avoid
Despite the abundance of mold factories available, only a handful of them (probably less than 5%) are appropriate. You are likely to face the following common issues:
- The injection defects of the product are not controlled within a reasonable range, such as dimensional deviation, flash or overflow, surface mismatch (usually at the location of the edge of sliders), product warping, etc.
- The mold cannot work smoothly, such as product ejection difficulty, mold temperature cannot be adjusted to the ideal state (waterway and oilway are not reasonably designed), mold design or material problems lead to mold life deviation.
- The product development cycle is too long, mainly because some problems are not foreseen in the early design stage, resulting in a long modification cycle in the later stage.
- There are also service and cooperation issues in the mold factory, which are largely caused by the factory’s lack of attention to the project or lack of service awareness.
Who the mold makers are
Let’s start by understanding who the mold makers are. A mold worker is a skilled worker who knows how to produce and assemble injection molds. A qualified mold worker has at least 2 or 3 years of study to master various skills such as metalworking and heat treatment, CAD software, fitter skills, mold structures, and troubleshooting, etc.
Education of the mold makers
In China or most places worldwide, mold makers are not usually required to have a college education. The most common degree for mold makers is a high school diploma. Some mold makers may also earn an associate’s or bachelor’s degree in a related field. Additionally, many mold makers complete apprenticeships to gain experience and knowledge, which can last 2 to 4 years.
The working conditions for mold makers can be challenging: noisy, dirty and greasy environments. High temperatures and sometimes injuries. They often work long hours to meet deadlines and customer requirements.
Mold making is a somewhat challenging profession, and there are different levels of competence among mold makers. However, the working conditions and wages of mold makers may not attract those who have the best academic performance.
Large mold companies vs. small mold shops
When you first approach an injection mold factory, you need to know how big they are, as different sizes have very different characteristics. The table below is a snapshot of what they look like:
|Number of employees||1-10||10-100||100-1000|
|Machining equipment||Mostly outsourced||Some outsourced, some in-door||Mostly in-door, some outsourced|
|CAD design ability||Mostly outsourced, Some can do CAD design on their own||Some have an internal designer team of 2-3 people||Some may have an internal designer team of 20-30 people|
|Expertise on mold making||Uncertain||Uncertain||High|
|Their attention on your project||High||Uncertain||Moderate|
|Trustworthy on Quality and on-time delivery||Uncertain||Uncertain||High|
Here are some more notes：
Number of employees
Small mold factories do not have redundant staff. This helps save costs, but also means that they may face staff shortages. They don’t have an office clerk to interface with you and it is usually the factory owner who is responsible for most projects, which helps you to communicate effectively.
Medium-sized mold factories have more employees, but the mold makers work mostly on their own. They have an office clerk to coordinate with you, but he or she doesn’t necessarily know a lot about molds, so your communication with the molders may not always be smooth. Also, the mold maker who works on your job may not be very skilled, so the work quality may suffer.
Large mold factories have a well-organized company structure and enough staff. They usually have teams to discuss technical solutions and collaborate on material sourcing, quality inspection and so on. This means your project is more likely to be done well and on time.
Quality system / Expertise on mold making
Large mold factories have better mold-making skills and expertise. They usually have quality systems like ISO 9001 in place, but they may skip some steps to save time and effort. They are unlikely to produce a lot of paperwork for EACH pair of molds they make.
Medium-sized mold factories are not necessarily superior to small ones. Many of them also claim to have quality systems like ISO 9001, but they do not implement them properly in reality. Their molders often work independently without much supervision or guidance.
Small mold factories have more flexibility in management, but can also be more unorganized. However, some molders in small factories are talented, so your vetting will be more on the human rather than on the factory. Because you are establishing direct contact with the molders, you can avoid some communication issues caused by the coordinator.
Their attention on your projects
Small mold factories are likely to pay more attention to your project as you are a big customer for them.
Medium-sized mold factories often depend on 2 or 3 large customers to sustain them, so you may not be a priority. And their company is more influenced by a few key people, and you need their support.
For large mold factories, because they have a dedicated coordinator or project manager for your project, they can provide a certain level of attention to small and medium-sized customers too.
Generally, small mold factories will probably give you more attention and cooperation in solving complex problems.
Small mold factories have less operating costs and profit expectations, so they offer the lowest prices. We have compared several times and the prices from different sized mold companies are roughly like this:
If a small mold factory charges $10,000 for a mold (as a reference point for comparison).
Then a medium-sized mold maker will charge $15,000-$20,000.
A large mold company will charge $20,000 – $25,000
5 aspects to examine and select plastic mold manufacturers
1. Get to know their business background, location and price
The first thing we need to know is the size of their company, and whether their offer is in line with the size of their company. If the price is not right, then there will be no point in continuing the communication.
You may want to request the mold makers to provide the cost breakdown, so you can compare them and see if each cost is accurate and reasonable. However, the large companies may refuse to do this because it may expose their high overhead and make them look bad.
You can use our online mold cost calculator to get an estimate of the reasonable cost for each item and the total price. This is only for reference, as different molds may have some variations in designs.
It is also important to know where the company is located, whether it is in an area where the mold industry is well-developed. This is because these areas have more people and equipment for design, processing, and so on, and are more likely to produce better mold companies. For example, Dongguan and Shenzhen in Guangdong, Ningbo in Zhejiang, and Kunshan in Jiangsu.
We also have a map of mold companies that shows our trust level, some cities we are reluctant to approach because we have bad experiences in the past, before understanding that some places have different folkways. Of course, this is not a fixed rule.
2. Test them with a difficult part
What this mean is not to use the parts you want to make to let them quote, but to use a product with a higher difficulty to let them quote.
The logic behind this is that it is very difficult to judge the skill or talent of a mold maker by the usual difficulty of the product, but why does this matter?
Well, if you only let them to do occasional small batches of simple products, this may not be a big deal. But if you want them to do large batches of simple products, or if you plan to work with them for a long time to develop more products, this will be more important.
Also, and this may be a bit of a personal bias, I think there is a correlation between the level of knowledge and the level of integrity of a mold maker.
3. Ask them to provide quality inspection report
See if the factory can provide inspection reports and correction plans for T0 samples (or even T1, T2 samples, etc.)
Generally, such inspection reports cover injection molding defects (e.g. flashes, warpage, weld line lines, etc.), whether key dimensions are within tolerance, and the appearance of the product (uniformity of surface texture, color, etc.).
This is because factories need to be in the habit of inspecting their own products, rather than relying on customers to do so. This will save you a lot of time and effort. But if you have to make trade-offs, this point is less important, because the small factories may be aware of the issues but do not have time to complete the report.
4. Ask them to deliver a DFM report
The DFM report can provide the basic design of the mold (e.g. gate type/location, ejector pin location, etc.) which will have a direct impact on the quality of the product.
The DFM report also provides a wall thickness/draft analysis, and suggests changes to the product design.
In addition, the DFM report will also include what injection molding defects are likely to occur in the product, and take countermeasures to reduce the extent of injection molding defects.
There are many small and medium-sized molders who do not know how to produce a DFM report, but it is important for future product quality assurance.
You may not need the DFM report for simple plastic parts, but it is beneficial to know that the factory has this capability.
5. Are they courteous and responsive?
You want to feel that they are interested in your project, that they understand your needs and expectations, and that they are willing to communicate with you throughout the process. That is why it is important that they are courteous and responsive when you contact them.
They listen to your questions and concerns, and answer them clearly and honestly. They show that they value your time and business, and that they care about your satisfaction.
They reply to your messages or calls as soon as possible, preferably within 24 hours. They provide you with the information or documents that you request, such as quotes, samples, or references. They update you on the progress of your project regularly, and inform you of any changes or issues that may arise. They follow up with you after the completion of your project, and ask for your feedback or suggestions.
Being courteous and responsive when contacting a mold maker can help you establish a good rapport and trust with them. It can also help you avoid misunderstandings, delays, or disputes that may affect the quality or delivery of your project. It can also increase your chances of having a successful and long-term partnership with them.
Have a reasonable expectation for a Chinese mold maker
In reality, especially if you are not a major customer, it will be hard to find a mold maker that satisfies all these criteria. If we have to compromise on some aspects, their importance would be as follows.
|Item||Level of importance|
|Business background, location and price||High|
|Test them with a difficult part||Medium|
|Ask them to provide quality inspection report||Low|
|Ask them to deliver a DFM report||High|
|Are they courteous and responsive||High|
Tips for Ensuring Quality and Delivery of Your Mold Project
When you are making the mold, you need to follow some steps to ensure the quality and delivery of your project.
First, you need to ask for a timetable from the mold maker before they start working on your mold. The timetable should include the milestones, deadlines, and deliverables of each stage of the mold-making process. If possible, you should also sign a contract with the mold maker that specifies the terms and conditions of your cooperation.
Second, you need to contact the mold maker regularly to ask for updates on their progress. You should also check if they are following the timetable and meeting the quality standards. If there are any changes or delays in the timetable, you should ask for the reasons and request a revised timetable.
Third, you should not be afraid to be persistent and assertive when contacting the mold maker. You are not being annoying, but rather showing your interest and involvement in your project. You need to do this from time to time to make sure that your project is done on time and according to your expectations.
(This post was originally written in Jan. 2020 and revised in Jun. 2023)