Do you know that you can insert mold plastic parts?  This process is called over molding and it lends itself when you need two or more different materials in the same part. It is very interesting and time saving process / concept mainly when we need accuracy and consistency in assembled parts like in smart meters for instance. 

What is insert molding: Insert molding is the process of injection molding plastic around any substrate or metal insert. There are many substrates used in insert molding, but the most popular is brass threaded inserts and bushing.  In addition, many companies make custom inserts that can be insert molded.  It is really left up to the imagination when deciding what type of inserts can be over molded. The benefit to insert molding is that parts can be mass produced faster than machining whole parts out of metal.  Even though insert molding adds to the cycle time (typically 15 seconds per insert) it is still much faster than CNC machining a part from a solid block.  Furthermore, by insert molding metals where necessary and replacing the rest of the part with plastic will in turn reduce the overall weight of the part. See the parts example below.

Plastic parts for Smart meters:

Following are the list of critical parameters to be considered during the product design, application, manufacturing, execution and its overall life cycle while keeping in mind the main factors like our environment, circular economy and sustainability.

Engineering plastic material selection criteria’s;

  • What is most important to the application, the right group or its characteristics
  • Choose the best family - is temperature a factor? How critical is cost?
  • Compare the mechanical properties - is tensile strength (resistance to being pulled apart) important?
  • Compare the mechanical properties - is flexural modulus (bending stiffness) important?
  • Compare the mechanical properties - is izod impact (toughness) important?
  • Compare the properties - is dielectric strength (electrical insulation) important?
  • Think about the application - is FDA compliance important?
  • Think about the application - is chemical resistance important?

Accordingly, smart grids promise large savings in energy and a more efficient control of electricity generation, distribution and consumption. However, to make the vision of smart grids true, additional components and systems must be integrated into the existing conventional power grid. The first step towards future smart grids is implementation of advanced metering infrastructure (AMI).  The main component of such an infrastructure is the smart meter.  Due to the need for a very large number of smart meters, the influence of these components on environmental sustainability of smart grids is expected to be significant.  Few examples of such plastic parts are shown below.

Insert Molding types;

  • Brass Bushings
  • Threaded Inserts
  • Magnets Over-molded
  • Bushings
  • Custom Inserts
  • Plastic over Plastic Substrate
  • Plastic Over Custom Inserts of any Material
  • Chemical Bond Over-molding
  • Plastic over Threaded Inserts
  • Mechanical Bond Over-molding
  • Medical Instrument Over-molding
  • Electronic Over-molding
  • Wire Over-molding

Design for Manufacturability: Design for Manufacturability (DFM), or more specifically analysis of a part design for its suitability to being injection molded, is performed to achieve the following:

  • Minimize Tooling Costs
  • Reduce Design Changes
  • Expedite the Manufacturing Process
  • Ensure Part Quality

Performing a manufacturability analysis on each injection molding project to be sure that the requested component is an appropriate candidate for injection molding.  The main objective is to produce the component as closely as possible to the original design intent, however in some instances modifications are needed to accommodate the fundamental requirements of good injection molding practice.  In these cases, we will discuss with the client suggested improvements to the design, or measures we may need to take in the production process, prior to initiating the mold production process.  This provides our customers with cost savings by minimizing tooling costs and design changes up front, and reduces overall project time. 

Mold making process: Due to the extremely efficient and advanced Molding System available today, the cost of precision CNC machined molds is very competitive for short run and prototype applications. Thus, often we could skip 3D Printing because the process is so fast, affordable, and uses the correct material intended in the final production components.  When compared to production tooling for bridge and higher volume production, at lower costs, and more importantly, it allows us in fast changing markets more time and flexibility to decide on production tooling and engineering changes based on market demands.