Moldagem por injeção de plástico de alta precisão para componentes de balanças digitais de bagagem

A digital luggage scale is a handheld electronic device that is designed to accurately weigh bags and suitcases. The device helps travelers avoid paying surcharges on overweight baggage.

It usually comes with a hook or strap that attaches to the handle of the bag you want to weigh. Once attached to the bag, the scale is raised to lift the bag from the ground. This provides instant weight readings of up to 110 lbs. (50kg) on an LCD screen.

Luggage scale manufacturers design these devices to be portable and lightweight, making them handy for just about anyone to operate. The compact nature of these devices makes it easy to fit them into a pocket or bag. The bulk of digital luggage scale components is made with durable plastic. The main components of a digital luggage weighing device are listed below.

• The Sensor or Load Cell: It is the core of the handheld device. It comprises a metal component that measures the deflection or deformation caused by the weight of the luggage.
• LCD Screen: The digital screen shows the weight of the suspended luggage. The reading can be in kg or lb. Some models will be backlit to improve visibility in low-light conditions.
• Luggage Scale Component Housing: This is the plastic handle that protects the internal electronics.
• Hanging mechanism: It can be an alloy hook, a webbing, or a nylon strap, designed to secure the luggage.
• Botões: All models will have power buttons to turn the device on or off. Some models will have additional buttons to reset the unit or switch the unit of measurement between kg and lb.
• Battery compartment: A small compartment often secured with a screw that holds the battery that powers the device.
• Circuit Board and Components: This is a processor that converts strain gauge data into digital numbers that are read off the LCD screen.

Requisitos do cliente

A digital luggage weighing device manufacturer approached First Mold requesting molds that would help them bring their products to life. The client wanted to mold a total of six different digital luggage weighing scale components. One of the molds was expected to mold a transparent material, which allows the digital screen below to be displayed.

The client wanted a mold for mass production. One of their requirements was that the digital luggage scale mold should last an upward of 500,000 runs. Additionally, the client wanted the digital luggage scale component housing to have a snap-fit design. For easy assembly, the tolerance must be ±0.05mm with an accuracy of ±0.02mm.

Another important requirement from the manufacturer was that the surface of the housing should have a gloss finish. Since the company was positioning itself as a global brand, the client wanted their products to have a premium feel.

Desafios

The first challenge that the First Mold project management team had to overcome with the project was deciding whether to create a single-cavity mold or a family mold. Choosing a family mold will allow the team to merge all six different components into a single mold. Also, family mold can prevent color differences between the distinct parts. However, if the team chooses a single-cavity mold, they will have to create six different molds for each of the client’s digital luggage scale components.

High-Gloss Surface Finish

Extra work goes into creating molds for high-gloss surfaces. The mold surface needs extra polishing, which requires more man-hours of work. Getting the polished surface can extend the delivery time. Therefore, it always presents an extra challenge for projects with a tight deadline.

Seleção de materiais

A digital luggage weighing scale is expected to undergo strain when in use. When used in an airport environment, it can be used to weigh thousands of bags daily. Therefore, it is important that the material used for production has excellent wear resistance for improved product durability.

Design For Manufacturability

The housing of the digital luggage scale featured rib-reinforced walls to further improve the rigidity to ensure that it doesn’t snap during operation. Also, the design featured large edge radii. The radii are an important feature that improves material flow, minimizes shrinkage, and reduces stress concentration. It enhances the overall strength of the part. However, large edge radii can also be the cause of defects like tearing or warping if not properly designed.

Solução

After multiple deliberations with the digital luggage scale manufacturer and weighing the pros and cons, First Mold’s project management team decided that a single-cavity mold is better suited for the manufacturer’s intent. While the use of family molds can prevent color differences, the client does not treat color differences as a major manufacturing concern because the product will undergo spray painting.

Family molds are faster in simultaneously producing multiple, different parts. However, they usually suffer from pressure imbalance, which leads to higher defect rates in certain components. The decision for a single-cavity mold was made due to the advantages it would offer to the manufacturer, including:

• Low production cost: The design of a single-cavity mold is usually simpler than a family mold. That simplicity in design translates to lower tooling costs because of the lower man-hours of work that will be required. The client’s budget favored single-cavity molds.
• Faster Lead Time: The simpler design also means that simple-cavity molds can be produced faster compared to a family mold. Faster lead time means the digital luggage scale manufacturer can start mass producing their products within the shortest possible time. The client also complained about working under a tight schedule and wanted the mold(s) completed quickly. Therefore, opting for single-cavity luggage scale component molds was an easy call.
• Fast trial adjustments: Modifications are easier and cheaper to effect on single-cavity molds than on family molds. Since the manufacturer also expressed during the discussion that they like to review and upgrade their products every two years, the single-cavity mold was a better fit.
• High yield rate: In single-cavity molds, there is no need to balance different geometries and parameters like temperature and pressure. This leads to higher yield and the least number of defects, compared to family molds.
• Lower cost of maintenance: Repairs of single-cavity molds will only be isolated to a specific mold and will not interrupt the production of other parts. However, in family molds, any repair will ground production. Since the client also supplies digital luggage scale components to other manufacturers, investing in a single-cavity mold was a way of futureproofing their supply chain.

Achieving High-Gloss Surface Finish

The reason why the manufacturer requested a high-gloss surface finish was that they wanted to cut down on post-processing. They wanted the surface to be ready for silk printing or spray painting after molding. To achieve the high-gloss surface finish, the team of First Mold engineers polished the surface of the mold with 12,000 grit sandpapers. The process required a lot of skill and precision to prevent defects. 

Picking the Right Material for Performance and Durability

The quality of any product begins with selecting the right material. First Mold team had a lengthy discussion on material selection with the client. Acrylonitrile Butadiene Styrene (ABS) eventually emerged as the best material for their digital luggage scale production. In terms of manufacturing, they can easily be machined, sanded, or glued for high-quality and detailed finishes.

ABS is 100% recyclable, too. Since the manufacturer was conscious about the environmental impact of their production, the use of ABS allowed them to reduce their environmental footprint by blending recycled materials with virgin plastics. The benefits of ABS use on the consumer end are also enormous.

• Relação custo-eficácia: The use of ABS makes it easy for manufacturers to produce high volumes of digital luggage scales at a cheaper rate. The low melting point makes high-speed injection molding efficient. These factors lower production time and costs.
• Leve: ABS is lightweight, a feature that is transferred to the product. Using this material ensures that the product is lightweight for easy mobility.
• High durability: ABS is rigid, sturdy, and resistant to impact and scratches. These features make it ideal for protecting the internal sensitive electronic components from rough handling and drops.
• Design flexibility: Unlike some other types of plastics, ABS can easily take up various colors and surface textures. This makes it ideal for spray painting, which the manufacturer intends to use as a surface finish.
• Environmental resistance: ABS is water-resistant and can operate under moderate temperature changes without deformation. Consequently, it can be used in different regions with diverse climates.

O que o cliente ganhou ao trabalhar com a First Mold

By working with First Mold engineers, the digital luggage scale manufacturer leveraged the team’s over 50 years of combined knowledge in mold-making to decide the type of mold that would offer them the best value for their project. The team offered clear and transparent communication and carried the client along through every step of the luggage scale component mold production process.

The clear communication and upfront research helped First Mold team deliver six sets of molds at a record time that exceeded the client’s expectations. Working with First Mold exposed the client and their team to modern technologies and innovations in injection molding. The best part of the collaboration, according to the client, was that their expectations were exceeded within their budget.

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