Improved E-Bike Design Through Low Pressure Molding Products and Processes

The Challenge

In March/April 2019, a Chinese manufacturer of electric shared bicycles was working to develop a new e-bike design that would reduce manufacturing costs and weight while improving aesthetics and reliability. The manufacturer’s goal was to have a fleet of redesigned e-bikes on the streets for the summer of 2020. Rented out by residents and tourists throughout China, these bikes remain outdoors in most weather conditions.

The manufacturer targeted two electronic components – the dashboard battery life indicator and the electronic battery lock -- for redesign to reduce their size and cost.

The e-bike manufacturer needed three things from the new design:

  1. Smaller, more aesthetically-pleasing, and weather-resistant electronic component assemblies.
  2. Easy-to-manufacture one-piece components that communicate battery life clearly and allow for simple battery unlock via a phone app.
  3. An improved manufacturing process that would reduce costs through improved production efficiency.

The e-bike company turned to their manufacturing partner to produce the prototype bike and address design and manufacturing goals. The manufacturing partner reached out to the KONIG Electronic Technology Company, one of Henkel’s professional low pressure molding and encapsulation solution providers, to solve the design and production challenges.

The Solution

KONIG recommended that the e-bike manufacturer use Henkel’s TECHNOMELT® Low Pressure Molding materials to replace potting in both assemblies. LPM delivers the same performance advantages as traditional potting without the drawbacks

In an LPM process, electronic parts enter a customized mold slightly larger than the part itself. The mold’s design incorporates dimensional and functional features desired for the final part in a process that takes just 30 seconds, a low-temperature, one-part hot melt adhesive is injected into the mold, covering the parts. The molding compound cools and hardens immediately, and the finished part is then removed from the mold.

As the final encapsulated product is contour-exact, the volume of LPM material consumed is significantly lower than potting material requirements. Unlike potting, TECHNOMELT® LPM requires no inventoried parts like housings and screws. And by creating a two-step molding process, manufacturers can apply two different colored layers of molding resins to a part.

The entire LPM operation takes place at low pressure, cycle time is short, and fine/fragile circuitry is not damaged. These polyamide or polyolefin hot melt adhesives provide exceptional electrical insulation, as well as temperature, vibration, moisture and solvent resistance. Many formulations are available in various standard and custom colors, and all protect electronics from the harshest environmental conditions including high humidity, long-term UV exposure, and extreme thermal cycling. 

Compared to traditional potting, the improved manufacturing efficiency and reduced assembly and component costs of LPM mean a lower total cost for this process. Traditional potting takes a lengthy seven-steps and requires custom-designing and molding a plastic case. The PCB or other electronics are inserted into the case and the two-component encapsulating or potting material is mixed and dispensed into the mold. Once the materials settle around the parts, the assembly is removed from the line and racked, waiting for cure to complete. Once cured, the potting material permanently protects the assembly. 

Looking at material costs alone, LPM appears more expensive than potting. But factoring in LPM’s speed and simplicity, manufacturers find this process often delivers lower overall production costs. TECHNOMELT® LPM is a reusable, sustainable manufacturing solution sourced from 100% green, 80% renewable raw materials. 

Exceptional Results

Henkel’s TECHNOMELT® low pressure molding products and processes improved electronic parts quality and allowed the manufacturer to attain their design goals and meet their summer 2020 production deadline.

The manufacturer:

  • Reduced the size and weight of both electronic components, and met the new dimensional requirements for the bike assembly.
  • Increased production efficiency:
    • New process was significantly faster than potting and required fewer parts. 
    • Cure took seconds, not hours, without time or real estate for racked parts.
  • Enhanced manufacturing process efficiency:
    • Tightly controlled, semi-automated process
    • Constant flow of no-mix LPM materials 
    • Consistent volume dispensed/coverage thickness 
    • Lower volume of materials required
  • Solved design challenges:
    • TECHNOMELT® LPM allowed over-molding in two different colors for the battery indicator. First application of clear amber TECHNOMELT® PA6208 N, ensured visibility of the three LCD battery-level lights. For aesthetic appeal, a second over mold with TECHNOMELT® PA6208 N Black covered the battery indicator except for the LED lights.
    • On the battery lock, only TECHNOMELT® PA6208 N BLACK was used as the design goal was purely aesthetic, size, and weight-related.
  • Reduced assembly cost by 13%:
    • Reduced materials usage (lower volume = cost reduction) 
    • Shorter processing time 
    • Fewer parts needed
  • Expedited product design-to-launch process and increased manufacturing efficiency. 
  • Created weather-proof, water-proof assembly, protecting from moisture penetration
  • Increased environmental friendliness 
    • less material = better for environment
    • renewable, recyclable materials

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