Wrinkle Gate in Injection Molding — What It Really Means (Cashew / Banana Gate Explained)

At          Guangdian Technology    ,    we see this term quite often in projects from India, the Middle East and some    European customers. Once you get used to it, you also understand what it implies:    the part usually has strict cosmetic requirements and the gate must be completely    hidden.

What Exactly Is a Wrinkle (Cashew) Gate?

In simple terms, a Wrinkle Gate is a curved tunnel gate. Instead of using    a straight tunnel like a conventional submarine gate, the tunnel bends in a    cashew- or banana-like shape so that the melt can sneak into the part from the    back or side.

Typical values we see on real automotive tools are:

• Tunnel diameter: 0.8–2.0 mm

• Tunnel length: 15–45 mm

• Curvature radius: around R8–R25

• Preferred materials: PP, TPO, PP+EPDM (good ductility to avoid gate breakage)

The whole purpose of this geometry is straightforward — let the melt enter the part    from a hidden direction and keep the A-surface perfectly clean.

Why Automotive Engineers Use Wrinkle / Cashew Gates

Anyone who has worked on automotive exterior or interior trim knows a simple rule:    if there is even a small gate mark on the visible surface, it can easily become a    customer issue. That is why curved tunnel gates are so popular in          automotive trim molds    .

Why Many Mold Makers Struggle With This Gate Type

On a 2D drawing, a cashew gate looks simple. In real life, making it reliable over    millions of shots is another story. Below are the pain points we see most often when    customers send us problem tools from other suppliers.

1. The Curved Tunnel Is Harder to Machine Than It Looks

Depending on the geometry, the insert may require 5-axis machining, EDM, split    inserts and careful polishing. If the tunnel is not smooth enough, you will see    gate sticking or rough break-off surfaces. If the geometry is off, you may not get    a clean degate at all.

2. The Most Common Failure: Gate Breaks Inside the Tunnel

Anyone who has experienced this knows how painful it is. Production stops, the mold    has to be opened, the insert has to be removed and cleaned, and the schedule takes a    hit. We usually find a combination of issues behind this:

• Curvature radius designed too tight

• Insert steel too brittle for repeated bending stress

• Gate diameter and length not balanced with material ductility

• Hot-to-cold transition area running at the wrong temperature

3. Steel Selection Has a Direct Impact on Insert Life

Cashew inserts are slender and work under repeated mechanical stress. Choosing the    wrong steel leads to early cracking or deformation. In our tools we typically use    steels such as FDAC, 1.2343 or S136H, combined with proper heat treatment, to keep    the insert both tough and dimensionally stable.

4. Hot-to-Cold Systems Need Real Project Experience

On many exterior parts, the hot runner cannot face the cosmetic surface directly.    Instead, you need a hot-to-cold transition block feeding a cold runner and then a    cashew tunnel. This structure looks simple on paper, but in reality it is one of the    key reasons why some molds run smoothly and others constantly struggle with burn    marks, short shots or gate failures.

Wrinkle Gate vs. Wrinkle Defects

Because of the word “wrinkle”, it is easy to confuse the gate name with actual    molding defects.

A Wrinkle Gate is a gating design — a curved tunnel    gate used to hide the gate location.
   A wrinkle defect is a surface issue — ripples,    hesitation marks or flow lines near the gate caused by temperature or process    problems.

When a drawing specifies “Wrinkle Gate”, the customer is asking for a hidden curved    gate, not reporting a defect.

Where We Use Wrinkle / Cashew Gates in Real Projects

In real automotive work, cashew gates only appear on certain parts, and each has its    own reason. A few examples from our shop:

• Wheel arches / fender flares — large PP parts with long flow      paths and grain surfaces where any gate mark would be obvious on the vehicle.

• Exterior trims — Class-A or textured areas where manual gate      trimming is not acceptable and visual consistency is critical.

• Interior trims — parts with vents and thin ribs where a gentler      melt entry helps avoid flow wrinkles and hesitation.

• Door handles — high-touch components where the user’s hand will      feel any imperfection if the gate is placed in the wrong area.

• Pillar trims — long, narrow parts that are sensitive to warpage      and benefit from more balanced flow paths.

• Bumpers and multi-shot components — zones where the hot tip      cannot face the cosmetic surface and a hot-to-cold plus cashew gate solution is      the safest choice.

Why Many Buyers Eventually Work with Guangdian Technology

Most customers do not choose us just because we can list many automotive components.    They choose us because of what sits behind those lists — the day-to-day experience of    building and troubleshooting complex gates in          mold manufacturing        projects.

• We have designed and run many cashew gate molds and know where they tend to fail.

• We combine 5-axis machining, EDM and careful polishing for accurate, durable inserts.

• We have strong experience with hot-to-cold runner layouts on exterior and interior trims.

• We have repaired tools from other suppliers where gate breakage or poor degating caused downtime.

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