How to Maintain Color Consistency in Rapid Prototyping Using Plastic Injection Molding

If you are investing in plastic injection molding as the manufacturing process for your rapid prototyping project, then you know all too well that achieving color consistency in massive production runs on plastic parts can be highly challenging. Ultimately, this can only be achieved if the rapid prototyping company using plastic injection molding maintains strict process control through each manufacturing stage. You may ask yourself why all providers don’t follow this mentality. The reason is simple: color interpretation is subjective, and this brings higher costs and requires more manpower.

The best rapid prototyping companies using plastic injection molding will execute the manufacturing process in optimal viewing conditions with the right light source, visual acuity, and they will take on a number of other considerations appropriate for the environment, color, and type of plastic. This article is intended to help management teams learn how to maintain color consistency in high volume orders requiring the rapid production of plastic injection molded parts.

Know How Production Volume Impacts Color in Plastic Injection Molding

The volume that you intend to pump out will dictate color consistency. This is a topic you definitely want to learn the details of because there are certain processing methods that are more apropos for smaller volume orders as opposed to mass produced projects that call for the manufacturing of thousands of parts. For example, certain resin suppliers will generally state minimum order quantities in contracts that apply to resins of the pre-compounded type. This is why commitments such as these only make sense when larger volumes are required.

Use Tested and Proven Standard Color Systems

Laszeray utilizes standard color systems such as RAL and Pantone to gauge and ready the colors of the plastic molded materials. When it comes to the industry leader of colored plastic chips, Pantone is the clear leader in producing shades of colored chips that perfect professional mixes and measured color pigments to ensure an exact match each time.

Using Pantone color chip samples offers brands a tremendous degree of value because they have standard reference numbers which removes the guesswork out of the mixing process and therefore removes the chance that human error will throw a flaw into the color. There are, literally, millions of color shades out there, so using standard reference numbers and associated color charts will guarantee product consistency with every manufacturing job.

Color Consistency in Plastic Injection Molding for Rapid Prototyping Demands an Understanding of Masterbatch

Masterbatch is a pigment that’s highly concentrated and used to make massive volumes of colored molding resin for plastic injection molding. The masterbatch pigment is mixed using a strict ratio of 24 parts of base material to one part masterbatch color. This is advantageous because a little bit of masterbatch can be stretched out and widely used. Finally, masterbatch is sold in two metric ton minimum order quantities and therefore reflects a mammoth quantity of finished plastic components.

What About Color Matching in a Rapid Prototyping Assembly?

Often in the assembly process within a rapid prototyping order, molded parts must maintain perfect color match. This is usually the case when two or more pieces join together. Sometimes manufacturers will use a family mold or they will paint the parts after the molding to ensure color consistency.

Family molds are multi-cavity tools that create every single part of an assembly in one simple cycle. When a family mold is used, the parts are guaranteed to be 100% the same color. However, family molds are more expensive and they take significantly more time to create. Another option would be to paint each piece once they have been molded. Usually manufacturers can create paint shades that match the base material. However, there is no guarantee for an exact match. Also, because painting is considered another step in the manufacturing process, this method takes even longer than using family molds, and is more expensive.

Using Custom Colors for Mixed Volumes in Plastic Injection Molding Rapid Prototyping

Laszeray offers three methods to create the colors of plastic injection molded parts. When it comes to lower volume, it is best to choose pigments mixed in a hopper. On the flip side greater color consistency can be achieved through the customization of masterbatch compounding (for larger volume projects).

When choosing hopper-mixed pigments, non-colored plastic pellets are mixed with a colored pigment in a hopper machine before the resin gets injected. However, be cognizant that there are three main things to look out for when using this method, and they are the following:

• Mixing Inconsistencies – Whenever workers add powdered-based pigments in a barrel, the distribution is never totally predictable or consistent due to the fact that specific areas will stick more compared to others.
• Powder Spotting – Since pigmented powder is extremely thin, it can easily burn when heated and this may result in dark spots on the finished pieces.
• Humidity Issues – Moisture from the atmosphere can compromise the resin mixture when pigment is added, so extra special care must be present.

When partnering with a plastic injection molding company that specializes in rapid prototyping, be sure to discuss these talking points to ensure color consistency is met.

Custom Color Consistency for High Volume Rapid Prototyping Projects

Laszeray has found that the most efficient way to produce high volumes of colored plastic molded parts is to utilize masterbatch, pre-mixed compounds, or an amalgamation of the two (but there are downsides to be aware of). Due to the fact that Masterbatch is so highly pigmented with a ratio of 24 to 1 of non-colored pellets and reflects 50 tons of finished pieces, this is a method that should only be used for projects with the highest volumes. If you are going to do multiple production runs, you may want to consider resin formulators to create custom colors. These have resin MOQs of one ton thus representing large volume pieces, however, these can be distributed out across multiple separate production runs. Your best move is to speak with our engineering team to determine the best approach based on all of the other factors surrounding your project.

Contact Laszeray for a Consultation on Rapid Prototyping and Plastic Injection Molding

Laszeray is an industry leader, creating custom colored plastic molded pieces for rapid prototyping projects. Give us a call today and tell us all about your project, and we will show you how we can help take your organization to the next level by creating superior products that will excel in the market.