Redesign of the Tim Hortons’ iconic coffee lid.

Tim Hortons Lids 13
3d printed SLA prototype versus injection molded part

3D Printing Canada's Coffee Lid

Written By: Ron Luther, Manufacturing Specialist - Oct 11, 2023

At Forge Labs, we pride ourselves on being able to speed up product development, making it possible for new ideas to be iterated and taken to market faster than ever.  In 2017, design company One Twenty Three West came to us with a challenge on a tight deadline - to help them produce CAD files and physical prototypes of their redesign of the classic Tim Hortons lid, in just a couple of weeks.

Design Process

The original Tim Hortons lids were disliked due to leakage and sharpness of the edge, which made the drinks easy to spill, and uncomfortable to drink from. They were also not made from a material that could be recycled; with over 2 billion of these lids being made every year, it was time for a change.

Over the span of only a couple of weeks, our design team translated their concept art into 3D models. From the provided sketches and schematics, we produced more than 20 unique CAD files, renders and 3D printed models for review.

123W had developed a wide range of novel concepts to try to address the issue of spillage.

concept for design of coffee lid

Initial concept for a Tim Hortons coffee lid with spill prevention

After 20+ iterations produced over the next couple weeks, they started getting closer to what would eventually become the final lid. The prominent maple leaf up top serves as both a spill reservoir, and as iconic reminder of the brand’s Canadian origins:

another iteration of a coffee lid design

Final concept for the lid, with a maple leaf shaped spill reservoir

Pictured below are a number of iterations and alternative concepts that Tim Horton's went through, before settling on the final maple leaf design:

3d printed prototypes, using stereolithography

High fidelity 3D printed prototypes, made using Stereolithography technology

Technology used for this project

For the 3D prints, Stereolithography (SLA) in Accura Xtreme White was selected, running on our 3D Systems Projet 6000 HD 3D printer. SLA was selected over FDM, SLS, or PolyJet for the ultra-fast turnaround time, suitability for producing thin walled parts, high resolution, and low cost - the perfect fit for high quality rapid prototyping.

Stereolithography 3d printing machines

Stereolithography lab, showing our fleet of 3D Systems Projet 6000 HD industrial additive machines.

Laser Speed

One of the main reasons we recommend Stereolithography (SLA) for prototyping is the speed. SLA is a laser-based resin 3D printing process, where a high-powered laser is used to initiate a photopolymer reaction in a vat of liquid resin, which ‘cures’ into a solid part wherever the laser hits it. The laser is directed by a high-speed galvo - the absence of a slow mechanical gantry makes it possible to print rapidly, going from CAD to high-quality visual prototypes extremely quickly.  Run at 100 microns, this part took only 2 hours to print. By comparison, in an FDM process, this part would take 4 hours at a comparable slice height (on a standard Prusa 3D printer):

Lid design in SLA slicer software

SLA print time: 1h 24m

Lid design in FDM Prusa slicer software

FDM print time: 3h 4m

Material Selection

For the prototypes, Accura Xtreme White was chosen as a suitable resin. With a bright white color, excellent durability and toughness comparable to Polypropylene or ABS plastics, the material prints fast for high throughput, resolves details with excellent fidelity, exhibits nice sidewall qualities, and most importantly, has a bright white finish that mimics the look of an injection molded part. Once printed, the 3D printed part was clear coated in a UV-resistant clear coat, to keep it from yellowing with exposure to the sun over time.

3D Printing thin features

With a wall thickness of only 0.8 mm, the final prototypes would be challenging to resolve in an FDM or SLS process without the part collapsing in on itself - even if it did survive, it would be very weak. By contrast, the final part printed in SLA exhibited good durability and some degree of flexibility. This, together with the tight tolerances of the SLA process (+/- 0.2 mm at this scale), made it possible to use the printed prototype to test fit onto the actual cups.

Support Removal

Another reason we chose to use SLA is the easily-removed support structures. Since our industrial SLA process prints below the surface of the resin, the part could be partially supported by the viscous resin itself - meaning that the supports used can have very fine, delicate touch points. By comparison, a ‘bottom-up’ style system with an inverted tray would produce much larger supports, leaving an undesirable ‘B’ surface on the bottom of the part where it was supported:

Image

Left: 3D Systems supports have small touchpoints, making removal easy and having negligible impact on surface finish. Right: Inverted SLA systems, such as Formlabs, leave supports that are thick and leave large touchpoint artifacts which increases post processing time.

Once the support was removed, the part was lightly sanded to remove the delicate touch points, leaving no noticeable ‘B’ or ‘A’ surface. This sparse support structure also enables cost savings - at only 5% the density of support of a Polyjet process (which would offer a comparably high resolution), the material usage is kept very low, resulting in a much more affordable part.

Today, the final lid design, now produced in a recyclable polypropylene, can be found on every Tim Horton’s coffee cup across Canada.