At Colourhouse, we’ve compiled the most common questions we receive from injection moulding companies and their customers. To better support you, we’ve created this comprehensive guide using a fictional project as an example. We hope this covers your key queries, but if you need more information, feel free to contact us—we’re always happy to help!

Purchasing Strategy for an Outdoor Plug Socket with Lid: A Comprehensive Guide for New Purchasers

Sourcing materials for a new project can be challenging, especially when you're tasked with balancing technical requirements and cost-efficiency. Drawing on our team’s experience and feedback from purchasers, we’ve put together 10 key considerations to guide you through the process. By following this strategy, you’ll be equipped to make informed purchasing decisions that may deliver the best results for your company.

Step 1: Polymer Selection

Choosing the right polymer is essential to the plug socket’s durability, flexibility, and cost. Each polymer offers unique properties, so it’s important to select the one that best fits your product’s requirements.

Common Polymers to Consider:

• PP (Polypropylene): Lightweight, flexible, ideal for living hinges (used in the lid), and cost-effective.
• PE (Polyethylene): Durable and flexible but has lower heat resistance.
• PC (Polycarbonate): Strong, clear, and highly UV-resistant but more expensive.
• ABS: Impact-resistant, suitable for solid parts, but not ideal for hinges.

Key Questions to Consider:

• Will the socket experience mechanical stress?
• Is transparency required for any part of the socket?
• How do we balance cost with performance for the chosen polymer?

Step 2: UV Protection

For outdoor use, UV protection is crucial to prevent the material from degrading due to sunlight exposure. Without adequate protection, plastics can become brittle, discoloured, or lose durability over time.

Considerations:

• UV Stabilisers: The amount of UV stabiliser needed depends on the product’s exposure to sunlight. More intense sunlight, such as in equatorial regions, requires higher levels of protection.
• Environmental Factors: The geographical location where the plug socket will be used plays a key role in determining UV stabiliser levels.

Key Questions to Consider:

• Where will the plug socket primarily be used?
• Will it be exposed to sunlight for long periods?

Step 3: Living Hinge Design

The lid’s living hinge will need to endure repeated use. Polypropylene is often the material of choice for such hinges because of its flexibility and resistance to fatigue.

Key Questions to Consider:

• How frequently will the lid be opened and closed?
• How much wear will the hinge experience over time?

Step 4: Colour Matching

The right colour is important not only for aesthetics but for long-term consistency across production batches. Some colours may fade faster than others, and the dye used must be compatible with the polymer and any additives (such as UV stabilisers).

Colour Matching:

• Ensure the masterbatch supplier can deliver the required colour consistency and UV durability.
• Be mindful of how the pigments may interact with UV stabilisers and other additives.

Key Questions to Consider:

• What colour and finish are required for the plug socket?
• Will colour matching be needed for the different components?

Step 5: Material Shrinkage and Tolerances

Polymers shrink when cooled, and the amount of shrinkage varies between materials. It’s important to factor in shrinkage during mould design.

Considerations:

• Ensure that the mould design accounts for the shrinkage rate of the chosen polymer.
• Collaborate with your masterbatch supplier to account for shrinkage variations.

Key Questions to Consider:

• How precise do the component’s dimensions need to be?
• Are there multiple parts that require tight tolerances for assembly?

Step 6: Legal and Regulatory Compliance

Your product must comply with the relevant regulations for the regions where it will be sold. This may include safety standards, environmental considerations, or specific material restrictions.

Regulatory Considerations:

• Safety and environmental regulations must be taken into account. For example, some additives, such as flame retardants, may be restricted in certain regions.
• Certifications, like FDA for food contact may be required depending on the product and it’s potential use.
• Chemical Inventory will ensure that the pigments used within the formulation are approved for use within the country where the product will be used.

Key Questions to Consider:

• Will the socket be sold in regions with specific regulatory requirements?
• Are there any certifications or environmental standards that must be met?

Step 7: Consultation with Masterbatch Supplier

At this stage, close collaboration with your masterbatch supplier is crucial. You’ll need to provide key details, such as the selected polymer, required UV protection levels, colour preferences, and regulatory compliance. This ensures that the masterbatch is tailored to your project’s needs.

Consideration of Addition Rates:

The addition rate refers to the percentage of masterbatch mixed with the base polymer. The right addition rate is essential for achieving optimal colour distribution, dosing accuracy, and overall material performance.

• Lower Addition Rates (e.g., 1%): These can lead to dosing issues and may require longer cycle times to ensure proper mixing, which can affect production efficiency.
• Higher Addition Rates (e.g., 3%): Increasing the addition rate improves dosing accuracy and enhances mixing during processing. This reduces scrap rates and provides better coverage.

Example:
A 1% white masterbatch with 60% titanium dioxide might introduce 25 pellets into the mix, whereas a 3% white masterbatch containing the same amount of titanium dioxide, introduces 75 pellets, resulting in better coverage and colour consistency.

Dosing Accuracy:

Higher addition rates also allow for greater dosing accuracy, reducing variation during production. Here’s a practical example:

• On a machine with a dosing capability of +/- 0.1 grams, a 1% addition rate would result in a variation of +/- 10%, meaning the actual amount dispensed could range from 0.9% to 1.1%.
• By increasing the addition rate to 3%, the same machine would have a variation of just +/- 3.33%, leading to more consistent results with less variation across the production cycle.

Additionally, increasing the masterbatch addition rate reduces the amount of polymer required to produce the component by 1% per 1% increase in the addition rate. This results in polymer cost savings for the client.

Conclusion:

Higher addition rates ensure better performance, improved dosing accuracy, and cost efficiency. Working with your masterbatch supplier to find the optimal addition rate will ensure your project runs smoothly and delivers the highest quality results.

A guide to this process can be found here : Colourhouse Guide to Developing the perfect Masterbatch

Step 8: Prototyping and Testing

Before full-scale production, prototyping allows you to test the masterbatch under real-world conditions.

Testing Focus:

• Mechanical performance: How well does the living hinge perform?
• UV resistance: Is the product durable enough for outdoor exposure?
• Regulatory compliance: Does the product meet required standards?

Step 9: Be Cautious of Colour Matching Offers

In the current climate, it may be tempting to save a few pence per kilogram by switching to a cheaper colour match after production. However, this decision can introduce significant risks, especially if you've inherited the project from another injection moulder who has already completed all the initial testing and trials.

• Lack of Product History: Competitors offering a cheaper colour match may not have access to the full product history, including the critical testing that validated the original masterbatch’s UV resistance, colour stability, and mechanical durability.
• Quality Compromises: Focusing solely on cost can lead to compromises in quality. The cheaper masterbatch may not contain the same pigments or additives, which can affect colour longevity, performance, and even regulatory compliance.

Key Questions to Consider:

• Does the competitor offering the colour match fully understand the technical requirements of the project?
• Have they repeated the necessary testing and trial steps to ensure the new masterbatch will perform to the same standards as the original?
• Is the cost saving worth the potential risks of product failure, fading, or regulatory non-compliance?
• Are you simply giving them a sample of your current masterbatch and polymer without ensuring that all technical aspects have been properly evaluated?

Step 10: Masterbatch Distributors vs. Manufacturers

You may have the option to purchase masterbatch from a distributor or manufacturer. Each has its pros and cons, but dealing directly with the manufacturer can provide better pricing, customised solutions, and more robust technical support.

Distributors:

• Distributors often add a markup to the masterbatch, meaning you could pay more than if you bought directly from the manufacturer.
• They may offer cheaper alternatives but might not guarantee the same quality or technical performance.

Manufacturer:

• Manufacturers typically provide more technical support and insight into product formulation.
• Pricing from a manufacturer should be competitive, and you avoid unnecessary markups.
• Direct contact allows for customised solutions, ensuring the masterbatch is tailored to your exact needs.

Key Questions to Consider:

• Are you paying a higher price due to a distributor’s markup, and would you get better value by purchasing directly from the manufacturer?
• Is the distributor offering the same quality formulation as the manufacturer, or are they cutting corners to maximise their margin?
• Would working with a manufacturer provide better technical support and long-term value?

Conclusion: The Importance of a Strategic Approach to Purchasing

As a purchaser, your role extends beyond securing the lowest price. By taking a strategic approach and collaborating with your supplier, you ensure that the outdoor plug socket is made to the highest quality, meets all regulations, and delivers long-term value to your company.