Tape Dispenser Part Analysis Part 2: Tape Roll

General Design Elements

This is a very simple part, but could have some sections thinned out and cored away to make lighter, save on material, etc.

Manufacturing Method

The cylindrical geometry of this part has both sides of the cylinder cored out to converge at a thin wall section in the middle of the part. Because this geometry is not able to be extruded and wouldn’t be efficient to make with any other forming method (compression molding etc.), this is certainly an injection molded part.

With some minor modifications to this part, this may be able to be extruded as a profile. The material usage per part would be slightly higher, but tooling cost and throughput would likely provide cost savings beyond material use.

Parting Line Location

With no witness line present to indicate a parting line along the flat side cylindrical side of the tape roll, we can deduce that the parting line runs along the bottom of the tape role. It is likely that the side of the tape roll closest to the gate (shown below) is where the parting line resides.

Gate Location

Based on the location of the gate in relation to the parting line on the tape roll, it is likely that a tunnel/ sub gate was used in this application. The main benefit of this style gate is that the part will be automatically de-gated when ejected, improving production efficiency. This comes at the additional mold cost of designing and machining this style gate. More on sub gates at the following link. https://www.basilius.com/blog/types-of-gating-for-injection-molding/#:~:text=Cashew%20Gate,-Much%20like%20a%20tunnel%20gate. .

Likely produced on a two plate cold runner mold.

Ejection

The tape roll is likely ejected via stripper plate, as there is no obvious ejector pin pads or ejector pin witness lines anywhere on the part. The stripper plate will distribute ejection force evenly across the bottom of the part where the largest cross sectional area is.

Material Selection

The tape roll could be made of a multitude of different materials. Based on a brief physical analysis, it is likely that the tape roll is also made of some low-cost amorphous material such as polystyrene or ABS (acrylonitrile butadiene styrene). The roll is quite stiff and has a “tin” sound when dropped or otherwise impacted. The material used for the tape mold is likely compounded with titanium dioxide (TiO2) in order to give it the opaque bright white color shown in the picture.

Final Thoughts

To summarize both the tape dispenser housing, and tape roll part analyses:

Overall, this assembly is well done, and leaves little room for improvement. The pass-through core mentioned in the tape dispenser housing blog (injection section) could decrease mold cost and complexity, without significantly changing the form or function of the dispenser itself. The tape roll is a simple part, and leaves little to be desired in terms of reasonable improvements.