Best Practices in Tooling for Ultimate Molding Success

Originally titled 'Best Practices in Tooling for Ultimate Molding Success'

Active project participation and management using a systems-engineering approach streamlines efforts and optimizes opportunities for molding success.

Anyone in the plastics industry whose job includes active project participation and management is aware of the three distinct players involved in a plastic injection molding production launch. They are the OEM (product), the molder, whether in-house or outsourced (process) and the tool shop (mold).

 

Certainly other parts of a molding production launch are important, and those items include the resin, material handling systems, injection molding machine, specific production environment required, value-added operations, packaging and more. But these are considered sub-sets to the primary three. Whether any or all of these disciplines are in-house or outsourced, each has a unique mindset and perspective.

Ideally, the OEM, molder and tool shop operate as one to streamline efforts and optimize the opportunities for success. However, anyone in the plastics industry whose job includes active project participation and management is aware that these three players can find themselves in adversarial positions over the myriad technical details and time-sensitive decisions that must be made. Operating as one can be a challenge. Even though all three parties have the same goal in mind (which is to make something and get paid for it), they all have differing sets of priorities.

The Roles

The OEM must focus on its completed and validated product being ready to ship on or before the launch date. The OEM project manager, for example, must oversee everything from coordinating the efforts of all supply companies that are involved in creating the product to managing and synchronizing the packaging, advertising and logistics. The OEM project manager also must account for last minute design or packaging changes from its marketing department.

The molder concentrates on the overall process it is projecting, which includes equipment capacity, personnel resources and the floor space that is required for pellet-to-part production (to packaging when required). The molder is absolutely reliant on the tool shop for the timely delivery of properly functioning and robust injection molds.

The tool shop concentrates on geometry and steel. The tool shop focuses on how to get resin in, cool it down and then get the part out as quickly and efficiently as possible. Of course, many additional considerations play into this process, including steel selection, the deployment of gating techniques, the potential of a hot-runner system, the strategic use of mold-construction methods to improve maintenance efficiencies and so on. However, to the non-toolmaker, the shop is responsible for the most costly of necessary evils: the injection mold.

To the non-toolmaker, the shop is responsible for the most costly of necessary evils: the injection mold.

When formal RFQs and RFPs go out, months and sometimes years of OEM research and testing have preceded them. The OEM understands its market’s needs and has developed, designed and tested a product to address those needs in a better or less expensive fashion than what is currently available. By accessing its roster of existing qualified suppliers and searching for appropriate new sources, the OEM seeks cost-effective manufacturing methods and any innovative techniques to apply to the new product design and part geometry.

Because the mold build is an isolated event, the tool shop has greater options for taking on projects that might be a little out of its sweet spot. For the molder, that is usually not an attractive or wise option. Custom molders must be relatively selective when it comes to pursuing molding opportunities. Much like a tool shop that has invested significant amounts of capital in machining and engineering technologies to accurately and repeatedly build specific styles of geometry, a processor invests in injection molding machines and ancillary equipment of a certain type/size range to mold accurate and repeatable parts. The molder judges the viability of a project based on identifying part geometry that is a good fit for existing production methods and, in many cases, existing equipment with open capacity.

Unified Force Against Failures

Those who have a few years of experience under their belt have likely lived through a finger-pointing event. A project runs into unforeseen challenges and the first inclination is to figure out who is at fault. For instance, the cycle time is 32 seconds but was projected at 24. Some might say it’s the molder’s fault because its machines or its process technicians are incompetent. Some might say its the tool shop’s fault because the cooling circuitry and steel selection are ineffective, and some might say its the OEM’s fault because its target pricing is not in line with the tooling budget and the aggressive cycle that the molder quoted. Regardless of individual opinion, all three participants are part of a potential failure, so everyone loses.

When significant money is on the table, all participants are wise to take every step as a unified force. The industrial-design phase of product development considers the features that attract and retain customers of the product. The design-for-manufacturing phase takes the industrial design and makes the required improvements for moldability. The mold-design phase creates the best tooling system based on project scope. One would think that if competent people with the best intentions orchestrated every phase that every project would be a pain-free winner, but that is obviously not what happens.

Systems Engineering Approach

Sussex IM (SIM) has a diverse portfolio of customers and a broad array of sizes and geometries. The majority of the products that it produces involve significant pre- and post-molding engagement with regard to value-added operations (like insert molding, in-mold decoration, downstream automated and manual assembly, packaging and fulfillment). This assortment of part styles, materials and purchased components mandates that it has the appropriate in-house resources to provide the best value to its customers through a comprehensive project scope analysis.

SIM invests in personnel to enable the best tooling practices for the ultimate molding success. The technical team includes project managers, design engineers with part and tooling experience and automation engineers. It has five journeyman toolmakers on staff as part of the engineering and preventive maintenance teams. Based on the scope of the project, SIM’s groups interrogate geometry looking to add or enhance features to facilitate efficient part handling and orientation for downstream operations. Just like any good tool shop, SIM employs a best-practices approach to improve areas for product stability, consistent wall thickness, appropriate draft, improved temperature control and reduced cycle times.

The key to any successful manufacturing project, and certainly to a project with multiple processes, is collaborative communication. That means that all supply partners, as a team, start envisioning and expressing the entire manufacturing process from the perspective of production-part geometry. Every good tool shop and every good molder understands this and does this, but all relevant parties should interrogate and consider the entire scope of the project process. This is a practical way to define systems engineering.

The key to any successful manufacturing project, and certainly to a project with multiple processes, is collaborative communication.

Project Interrogation

Although difficult to do within the frantic pace of quoting, the entire scope of a project should be defined to legitimately determine cycle times, the impact of critical dimensions, validation requirements and tooling costs. However, the real world of manufacturing is not so organized, well-scheduled or patient.

Many RFQs start a bit informally. The OEM project manager contacts a few mold-building sources, shares the initial part data and forecasted volumes and simply needs “a ballpark number.” The tool shop looks over part geometry quickly and compares it to other jobs that have a few similarities. Maybe the toolmaker gets a couple of answers to the stock questions: Will the system use a hot runner? What is the cavitation? Is it better to jump the threads or auto-unscrew them? What are the surface-finish requirements? But, details are not important yet. It is likely that the project is still in the OEM’s evaluation stage. All that the OEM wants is a budgetary number. In these situations, the geometry often is not frozen and the estimate is needed right away.

What happens to the part after it is ejected? Will it need to be reoriented? Which performance functions need to be validated and what is the best way to do that? In which order should the value-added steps be sequenced? Are there any part features that can be added to the geometry to make any of the downstream events more efficient? Is the multi-cavity mold laid out in the spacing and configuration that the downstream fixtures and operations can accommodate? In many cases, answers bring more questions.

This is also the best time to define and understand quality objectives. From a part performance perspective, what are the critical dimensions and tolerances? Many OEM product designers like to answer that question with, “Every dimension is critical,” believing that this statement affords complete CYA protection. Making every dimension critical absolutely ensures three things: arguments, extra time and extra cost.

Making every dimension critical absolutely ensures three things: arguments, extra time and extra cost.

What if the OEM requires a formal PPAP, who is paying? Did the molder or the toolmaker include PPAP in their quote? Unless it is part of the RFQ (and often it is not), not one of the three players will assume financial responsibility for the required metrology events, documentation and man-hours. When part metrology uncovers a dimension or flatness specification that cannot be corrected via altering the process, that means that a steel adjustment is necessary. The tool shop will not assume responsibility, as it built to the print. The molder will not pay, as it did not design the part or pick the resin, and the OEM does not want to pay either. That is why the OEM went to the experts and believes that the toolmaker and the molder are responsible.

Unfortunately, a clear solution to this problem does not exist. Manufacturing runs this way in every industry. OEMs get quotes from multiple sources on multiple projects and most of them never get off the ground. An OEM chooses which new products to release based on the projected return on investment, and the only way to judge feasibility is to get quotes for manufacturing costs and lead times. Project engineers and designers come up with preliminary concepts based on input from marketing and sales. The quoting process begins, so someone in an office can tell someone else in a bigger office that “tooling will be around a hundred twenty grand and piece part should be just under a buck fifty, based on the eight sources who supplied proposals.” If the numbers make sense, the project may get the green light.

Several associates working on the OEM side have indicated that the average number of projects launched versus the number of projects researched and quoted is about one in 12 to one in 16. That makes for a great deal of time studying and quoting. OEMs can not launch every idea into a new product, and they can not fully develop every single new product idea into a complete 3D database with detailed part prints, appropriate tolerances, flatness, surface finishes and projected shrink. They can not define the exact scope of their project regarding cavitation, cycle time, downstream events, packaging, projected annual volumes and the life of the program. Part of the OEM’s homework is engaging with the tool shop and the molder to get answers to some of their questions to see if it’s financially worth investing more time and money to get answers to all of their questions.

The smartest thing a tool shop and a molder can do is be intelligent, proactive and honest. It is wise to provide answers to the RFQ that reflect best effort. Ask questions even when there is no answer. Document both the known and the unknown. Craft proposals based on the information shared and note what is not included in the quote and how eventually it will be addressed. On the other hand, there is a theory that quotes should be low when there is a poorly defined RFQ and then nickel and dime the customer with all the tasks that it did not define, including PPAP, metrology, sampling, steel adjustments and expedited charges. It is up to the moldmaker to decide which strategy works best for its business at the time of the quote and for the long term.

The smartest thing a tool shop and a molder can do is be intelligent, proactive and honest. It is wise to give the RFQ answers that reflect best effort. Ask questions even when there is no answer. Document the knowns and the unknowns.

About the Contributor

 

John Berg

John Berg is director of marketing at Sussex IM.

 

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