The burden of hose connector part design and design for manufacturability has shifted from the OEM to the tier-1 supplier and their injection molding partner.  Throughout this post we’ll discuss the reasons behind this shift, what makes a fluid connector technically complex, and the expertise your molding partner needs to deliver a stable and repeatable part.

Design Responsibilities Shifts to the Tier-1 Suppliers

Engineering resources at automotive OEMs have shifted away from “classic” part design and toward strategic priorities, such as electrification.  As a result, the burden of part design and design for manufacturability is falling more and more to you—the tier 1 supplier—and your injection molding partner.  Since so much production has gone to low-cost countries it’s even harder to find a molding partner with local expertise in part design, tool design, and processing.

Automotive Barbed Hose Connector Specs Tighten

Fluid routing specs have really tightened over the past decade.  OEM teams tend to ratchet up roundness and concentricity specs every time an end-user failure occurs.  Now the specs on connectors are much higher than the hoses that they attach to!

It’s Challenging to Produce Round Plastic Parts To-Spec and On-Budget

Injection molding is a dance between quality, cycle time, and cost.  All three are tightly wound together.  Experienced tool designers and molding partners will tell you that it’s really tricky to produce round parts.  It looks easy but plays hard.  This is because residual stresses in the part can make it challenging to hit the specs, which can lead to longer cycle times to let the part cool, which can increase the cost.

Residual stresses can warp round parts (like fluid connectors) after they are released from the mold.  This can be offset by exotic materials and longer cooling cycles, but that also drives up cost.

Early Recognition of Complicated Fluid Connector Designs Is Crucial

Some design elements can make a fluid connector very tricky to produce on-time, on-budget, and to-spec. These include varying wall thicknesses, sharp transitions in geometry, small port sizes, and unreasonably tight tolerances/ GD&T specs.

The trick is to spot these very early in the quote process, and a top-notch molding partner will do just that. Catching it early is key because small changes to part design can avoid headaches down the road. These headaches can include very long PPAP time lines, high PPM rates, and having to ask the OEM for a deviation.

Injection Molding Tool Design Can Offset Complex Geometries

Hopefully most recommended design tweaks can be accommodated.  If not, an experienced injection molding partner can overcome many challenges through tool design.

Quality tool engineers can balance melt flow and reduce cycle times with hot runner systems, increase cooling capacity with copper cores and forced air flows, and produce precise round parts with out-of-round tools (what??).  Yes, you read that correctly.

Depending on the part design, material flow, and residual stresses, sometimes it takes an out-of-round tool to produce precision round parts like fluid connectors.  Molding partners that don’t know this can set themselves and their customers up for a very long and hard journey.

Finding the Right Injection Molding Partner

If getting the fluid connector done right is your primary driver, then make sure you choose the right molding supplier.  If they aren’t asking you lots of questions about wall thicknesses, sharp transitions, knife edges, tolerances & technical specs, gate locations, and materials, then they probably are not doing an in-depth part feasibility up front.  That should send off warning bells.

Ammex Plastics has been tooling up and supplying hose connectors for 20 years, has shipped millions of parts, and runs at a PPM rate of <2.  If you’re looking for a new or alternate molding partner, head over to our Contact Us page today, and we’ll get back with you ASAP.