A Scientific Approach to Product Onboarding 

Whether you have a new product or are transferring a mold, onboarding is a critical step for ensuring consistent and repeatable production of products that meet your specifications. At Noble Plastics, we take a scientific approach to remove uncertainty in tooling, processes, and measurement tools that can negatively impact quality. Delivery of high-quality products that meet your requirements is our number one goal.

Trusted Partners in Mold Design and Building

Having the right tooling makes all the difference in the quality of your product. Tooling is your biggest investment, so designing and building it with precision and accuracy are critical to ensure your parts are molded flawlessly.

We work with trusted third-party domestic and overseas vendors to help customers meet specific requirements, including budgets and timeline needs. We ensure that every vendor has capabilities that meet our needs before starting the process. Tooling partners must go through an approval process, including providing case studies of their work and signing an NDA.

We work closely with them, keeping lines of communication open to ensure the molds are designed and manufactured to specifications. Our overseas mold builders have liaisons that operate during our business hours to provide the level of communication we require.

We perform design for manufacturability (DFM) evaluations as part of our systems engineering approach to the onboarding process before the tooling is designed and built. This allows us to address any complex issues that may add unnecessary costs to the mold, as well as uncover any errors in the part design.

Once our partners are contracted to build a mold, we do regular design reviews with them from the initial concept (e.g., number of cavities and layout) through detailed mold design (e.g., mold support structure, cooling structure, runner and gate design, slide mechanisms, hydraulic mechanisms) using a standardized approach. We also ensure that industry-standard components are used, and molds are compatible with our systems. These reviews provide consistency from mold to mold and safeguard our customer’s investments in their tooling.

Transferring Tooling With A Focus On Quality

Many of our customers have come to us from other injection molders, so we understand that moving your plastic injection molded product to a new supplier can be daunting. At Noble Plastics, our Bold Mold Transfer Process provides a systematic road map to ensure the quality of your parts is maintained. Below, we discuss the statistical processes and controls that are used to ensure the product from your transferred mold meets your requirements.

Tooling Take Over

Once we receive it, the tooling will be inspected and approved by the customer before sampling. We request historic parts from the previous molder so that we can measure them to provide a baseline. We will run a small sample of parts to ensure the process is correct and we can match the previously molded parts.

Capability Studies

On every tool we take over, we perform capability studies. A capability study is a statistical analysis that is used to determine if a system can meet a particular set of requirements. The requirements are typically numerical values with a minimum or maximum value (tolerances). For injection molding, we are verifying that the injection molding process and tooling can repeatably produce parts that match those that were previously molded.

We will generally mold forty consecutive shots, which are labeled in the order they were produced.  We then measure them in random order to mitigate any measurement bias. We use a data analysis software called Minitab to tell us statistically how consistent our process is. We look at the Cpk or capability index. This tells us about the relationship between the product measurements, the minimum and maximum acceptable values, and how centered that data is within those limits. The Cpk shows how many standard deviations the specification limits are from the center of the process. A CPK of 1.0 means that the dispersion of your measurement curve is centered and spans the upper and lower limits of your specification – there is no wiggle room. We strive for a Cpk of 1.33 or greater.

Scientific Process Development

While the mold is a critical component for injection molding, the process is equally important. We take a scientific approach to create robust, repeatable processes. The scientific process development is a framework of decision-making used to develop molding processes that will meet our customers and our internal requirements. Although high-tech equipment can help with some process issues, scientific molding primarily relies on the knowledge of engineers and processors who specialize in it. Our employees are trained by RJG and have completed various levels of training, including master molder level.

Scientific molding involves evaluating the injection molding process from the plastic point of view in a systematic manner so that variables are evaluated scientifically and not qualitatively. We follow general process development rules of thumb and use data from vendors for material setpoints (e.g., dryness, temperature), but we also depend heavily on statistics. For example, if we have a part with a dimension that is challenging to hit repeatedly, we will perform a Design of Experiment (DOE). This systematic, statistical method allows us to study the relationship between input process variables (e.g., material, injection speed, melt temperature) and results or output variables.

Statistical Process Control

We monitor deviations in our processes with statistical process control (SPC). Statistical process charting is crucial for understanding process capabilities, identifying unwanted variations, and refining our processes.

We identify a process that impacts the final product and determine the measurable attributes of that process, for example, a specific dimension on a part. We will have already performed a Gage R&R study on the measuring tool (see below), so we know the amount of variation due to it. We will determine our sample size and perform the measurements on the parts. The resulting chart, which has a central line for the average, an upper control limit, and a lower control limit, will tell us how stable our process is. As we continue to produce and measure parts, we look for trends that show the process is moving toward one of the control limits. As long as the process remains statistically capable, it is acceptable to run, and we continue to monitor it to ensure the process remains stable.

Gage R&R Studies

We have seen the importance of a scientific approach to tooling and processes for improving part consistency and accuracy, but the measurement tools we use to evaluate our processes must also be accurate. When measuring parts, we must show how much variation our tools bring into the system. If a measurement is off, we need to know how much is caused by our process and how much is caused by the variability of the measurement device. Gage repeatability and reproducibility (gage R&R or GR&R) studies are used to determine the variance in the measuring system, such as calipers. Repeatability is the ability of the measuring device to produce the same result with every measurement. Reproducibility is similar but involves the ability of multiple people using the same device to take measurements and get the same results. The results are a ratio of the repeatability and reproducibility and the overall variation.

Gage R&R studies are performed on our precision hand tools, including:

  • Digital calipers
  • Micrometers
  • Height stands
  • Dial bore gauges

Other advanced technologies that are regularly calibrated include a Brown & Sharpe CMM, which has a repeatability to 1.7 µm and accuracy to 8 µm, and a Keyence Image Measurement system, which has a repeatability to 2 µm and accuracy to 5 µm.

Trust Your Injection Molding to Noble Plastics

When it comes to onboarding new products and transferring molds, we have the experience to deliver. Our systematic and scientific approach to tooling, process development, and statistical process control reduces surprises that can impact quality. Our repeatable processes ensure your product requirements are met consistently. Contact us to learn more.

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