Injection Mold Design

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Our Injection Mold Design

Injection mold design is the engineering process of creating precise, durable molds that determine the quality, efficiency, and cost-effectiveness of plastic injection molded products. LZ Tooling specialises in designing high-performance molds that meet custom requirements for a wide range of industries.

With 30 years of experience in the injection molding, injection mold design, and mold making industry. LZ Tooling has established a great reputation for precision and reliability. We fully understand that the quality of an injection mold directly determines the quality and efficiency, as well as the cost of molding products.

As molds account for a high portion of production cost, their durability and service life are a major contributing factor to overall competitiveness.

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Our mold design can ensure the optical effect, good process cycle time, waste reduction, and the post-process is relatively easy. At LZ Tooling, our engineering department uses a combined 30+ years of expertise in tool designing, constructing & material evaluation, alongside emphasis on automation & quality assurance.

From new mold development to modification and maintenance, we can offer you comprehensive support, helping customers bring projects to life faster and at lower cost. We’re here to be your trusted partner in precision mold solutions.

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Mold Design Steps

When you select LZ Tooling, you have an expert partner who knows how to simplify your injection mold design from concept to production over 30 years. We expedite every step – from design, fabrication, testing, and maintenance – delivering efficient, reliable, and tailored mold solutions.

#1. Send your product design

# Send your 3D files in STL/STP/STEP/IGS format. This helps us quickly start to get involved in your design.

# Send your samples to us, and we will work out the 3D file as per your samples.

# No 3D file and sample, no worry, we can do the drawing as per your product’s ideas/drafts/sketches.

#2. Analyze Product drawings

We will do a detailed study of your product requirements based on 2D/3D drawing files. This includes:

The appearance and overall shape of the product
Product Dimension, Tolerances, and benches for design
Technical specifications, performance requirements
Type of plastic, the rate of shrinkage, and colour selection
Surface finish requirements, such as texture, polishing, or painting
Assembly and fit with other parts
Expected volume and cost-efficiency targets for production

This is a comprehensive evaluation that helps ensure the mold design is precise, durable, and completely aligned with your project goals.

#3. Design for Manufacturability (DFM)

Design for Manufacturability (DFM) plays a vital role in injection mold design, helping reduce costs and accelerate project timelines. A strong DFM approach at the project’s start ensures smoother execution, fewer errors, and higher efficiency.

At LZ Tooling, our experienced tool design team applies proven expertise to achieve precision and cost control. We utilise advanced engineering software, including SolidWorks, PROE, UG, AutoCAD, and CorelDRAW, to deliver reliable, optimised mold solutions.

#4. Mold Steel Selecting

The selection of mold steel is an important factor in injection mold design that directly influences the life of molds, as well as the quality and efficiency of the production. At LZ Tooling, we choose steel according to product design, estimated volume of production, and surface finish. High-quality steels such as P20, H13, and 420 stainless are commonly used to ensure durability, precision, and wear or corrosion resistance.

For high volume projects, premium steels can ensure longer service life and low maintenance costs, while for prototypes or short runs, specially softer materials such as aluminum may be used for cost efficiency and more rapid lead times.

#5. Mold Materials Selecting

Choosing a suitable molding material is critical to the final product’s performance, appearance, and cost tradeoff. At LZ Tooling, we closely consider attributes like mechanical strength, flexibility, heat-resistance, shrinkage, and chemical compatibility in the injection mold design stage.

Commonly used resins are ABS, PA, PC, PEK, PMMA, and TPE (polyethylene terephthalate), with different applications and several industries. Material selection also takes into account color, surface finish, and regulations. By ensuring the appropriate resin is matched to the demands of the product, we guarantee consistent quality, durability, and effective cost production on every project.

#6. Determine cavity amount

The number of mold cavities is a scientific question dictated by a combination of technical and economic factors. Key factors include:

Planned quantity to be produced (monthly or monthly effort).
Side core pulling and treatment method.
Mold size and the distance between the tie rods of the injection molding machine
Product weight and the injection capacity of the machine.
Required clamping force.
Product Accuracy And Tolerance Requirements
Product Color and potential material separation requirements.
Overall economic benefit and Productivity of each mold.
Design of the cooling system and the ability of the calendar to show a uniform temperature.
Ease of maintenance and the mold durability over the long term of use.

Once this number of cavities is determined, we optimise the arrangement and layout of the cavities to provide efficient patterns for moulding cycles and stability in quality production.

#7. Determine parting surface and parting line

In choosing the parting surface in injection mold design, the following principles, if possible, should be followed:

The parting surface shouldn’t leave an impression on the product.
For parts with stringent aesthetic requirements, be mindful when pulling out the parting line so that the line has very little visual impact.
The design should assist in preserving product dimensional correctness and structural integrity.
Parting surface should make the machining of the mold easy, more particularly, cavity and core processing.
It should support the layout and functionality of the gating, venting, and cooling systems.
The design must ensure easy demoulding, i.e, the moulded parts stay on the movable half of the mold.
It should provide the convenience of placing and fixing metal inserts where needed.
The parting surface should reduce flash and minimise post-processing operations for efficient production.

The selection to ensure the mold durability and maintenance, and to make sure that wear-prone areas give access for repair or replacement.

#8. Determine mold base

Choosing the right mold base is crucial as it supports the cavity, core and key components. Selection is based on product size, the structure of the products, anticipated life of molds, and volume of production. A good mold base means stability and accuracy and room for systems such as cooling and ejection. Standard bases for lower cost and/or complex designs can be fitted with custom made bases.

#9. Mold gating system

The gating system design can be divided into main runner selection, sub runner sectional shape and size selection, and, what matters most, gate selection. Gate placement also has a direct impact on the quality of molding, flow balance, and process efficiency.

Principles used for selecting gate location:

Place the gate on the parting surface whenever possible so that a gate can be more easily machined and trimmed.
Keep the gate to cavity distance the same and the flow path minimal to minimize pressure loss.
Position the gate toward the thicker sections (more dense) and larger sections. Filling is better, and defects are reduced.
Care must be taken to avoid direct impact against cavity walls, core, or inserts so as not to produce deformations.
Minimise weld lines – If you have to have weld lines, try to put them in non-critical parts.
Do make sure that the gate direction allows balanced flow and venting of trapped gas.
Design gates to be easily removed without looking bad.
Think about the Multi-cavity balance – make sure that each cavity fills evenly.

As well as smooth flow, you also need to control the shear stress, yet having too small a gate size may cause a large separation between the nitrogen release and the weld.

#10. Surface Finishing

Surface finishing is a very important step in the injection mold design and manufacturing of a mold as it will have a direct relation to product appearance and performance. Proper finishing supports good cavity walling, frictionless demoulding and high-quality finish on the parts moulded.

Depending on the needs of the product produced, finishing can involve polishing, texturing, sandblasting or applying a coating to impart specific amounts of gloss, texture, or wear resistance. High-precision finishing helps improve mold life as well as prevent defects like scratches or flow marks and improves overall production quality consistency.

#11. Cooling system

Designing the cooling system is a complex task; a balance between cooling efficiency, uniformity, and effects on the overall structure of the mold must be made. A well-designed system enhances product quality, cuts cycle time, and prolongs mold life.

Key considerations include:

Layout and type of cooling system.
Good positioning and dimensions of cooling channels.
Cooling of critical areas, like cores and inserts.
Cooling-Side slider and side cores
Selection and design of cooling parts with standard elements.
Reliable sealing structures to counter leakage
Easy maintenance and cleaning of the cooling channels to provide long-term performance.

#12. Mold venting

The mold venting system is vital to molding because it allows the successful discharge of the air and gases from the cavity. Common venting methods include:

Exhaust slots – Individual slots in the cavity, which are usually positioned on the last filling areas. Their depth and width are dependent on the plastic material and are designed to let air release without causing flash.

Clearances and plugs – Natural gaps between cores, inserts, and ejector pins can serve as exhaust paths. In some cases, special exhaust plugs are added for better venting.

Vent inserts– These are used in areas where a vacuum is prone to occur to prevent the vacuum from changing the shape of components and ensuring product stability.

#13. Ejection system

Product ejection may be mechanical, hydraulic, or pneumatic. As the final step in the injection molding process, proper ejection is vital in order to avoid defects and ensure product quality.

Principles for design of ejector systems:

Place thrust points near the core or near the areas that are difficult to release, and arrange them as equally as possible.
Apply force to rigid sections (ribs, flanges, edges) so as not to deform.
Do not eject on thin walls; use push plates for the shells/cylinder parts.
Maintaining appearance by keeping the marks of ejectors on hidden surfaces, especially clear parts.
To balance stress and lessen the effects of vacuum, use some form of combined ejection (pins, plates, sleeves, or air assist).
Design for ease of maintenance as well as replacement of ejector components.
Must ensure that ejection is smooth and stable to reduce the cycle time and aid efficiency.

#14. Split the mold and draw 2D drawing

Split the mold, making the 2D drawing file of every part as the processing drawing file. When drawing the diagram of the cavity or core, it is required to take into account whether the dimensions and tolerances of the given moulding and the angles are compatible. At the same time, the manufacturing of the cavity and core in the processing phase and the mechanical properties and reliability in the later phase also need to be completed.

#15. Proofread and countersign drawings

After completion of the mold design, engineers need to carefully review the overall structure, working, and feasibility compared to the customer’s design specs and requirements. After verification, the injection mold design drawing should be submitted to the customer for the customer’s approval. Production can start only after approval is given. If any important changes are requested, the design then has to be revised and resubmitted until the customer is completely satisfied.

LZ Tooling is engaged in injection mold design, providing technical support and design insights to help create accurate and efficient molds. By collaborating with clients, LZ Tooling assists in optimising mold geometry, selecting suitable materials, and improving overall production efficiency, ensuring that plastic components meet functional and quality requirements across industries.

Have a customized injection molding parts ?

If you have customized plastic parts, pls send an inquiry to us, we will follow up and provide fast and professional mold design solution for your projects.

Start Your Mold Design With Us

We are looking forward to receiving your inquiry/comments/feedback/consultation. We will provide fast and professional injection mold design and respond to your questions.