Plain cone
- Simplest inside surface, easiest to wipe clean
- Works fine in an open container
- Glugs and spits when the stem seals a neck
Molded part guide: funnels
Injection Molded Funnels
A funnel is a cone and a tube, which sounds like the easiest part in this list. In the tool it is a long, thin, deeply drawn shape that grips its core all the way down. In use it either flows freely or it burps and spits, and the difference is one small feature inside the cone.
Cone and stem
A long draw and a long core
Workshop funnels, laboratory funnels, filling funnels, and oil funnels.
The cone is deep, thin, and tapered, so the plastic shrinks onto the core along its whole length as it cools. That grip is what makes a cone a tough part to eject. The taper already built into the shape helps, but the inside surface is also polished along the pull direction, and the pushing force is spread around the rim so the thin cone is not dented on the way out.
The stem is even harder. It is a long, narrow tube formed by a long thin core pin, and that pin is only held at one end. Melt rushing past pushes it sideways, so the stem ends up thicker on one side and thinner on the other. A stem that is supported at its far end, or kept short, stays concentric.
In use the real complaint is air. Pour liquid into a funnel whose stem is sitting in a bottle neck, and the air already in the bottle has nowhere to go except back up the same stem the liquid is coming down. The two fight, and the funnel glugs, stops, and spits liquid back at you.
The fix is a channel molded up the inside of the cone and along the stem, so air has its own path out while liquid runs down. It is a small feature that changes the whole experience of using the part. Nesting is the last consideration: identical cones stack so tightly that they stick, so small steps on the outside hold each funnel a little clear of the next.
Features
Funnel features and what each one does
A simple shape with four features that matter.
| Feature | Purpose | Design note |
|---|---|---|
| Tapered cone | Collects and guides liquid | Long draw, polished along the pull direction |
| Stem | Delivers into the neck | Formed by a long core pin that wants to wander |
| Air channel | Lets air escape upward | Runs up the inside of the cone and along the stem |
| Rim | Stiffens the wide opening | Return flange so the cone keeps its round shape |
| Nesting steps | Stacks that separate | Small steps on the outside of the cone |
Flow
Air coming up fights liquid going down
A funnel in a bottle neck seals the bottle, and the trapped air has to come back through the stem.
- Liquid running down the stem blocks the only path the trapped air has
- The two take turns, which is the glugging and spitting people complain about
- A channel molded up the inside of the cone gives air its own way out
- The same channel lets the funnel sit in a neck without sealing it
Cone inside
Plain cone or channelled cone
A channel costs nothing to mold and changes how the funnel behaves.
Channelled cone
- Air escapes while liquid keeps running
- Fills a sealed container steadily
- One more surface to clean inside the cone
Drawing
What to send with a funnel
Where it is used decides the stem and the channel.
Funnel CAD, or the opening and stem sizes you need
What it pours into, an open vessel or a sealed neck
Liquid type, temperature, and anything it attacks
Whether funnels are stacked for shipping or storage
Filter or strainer features, if any
Expected annual volume
Keep reading
Related guides
Other deep parts, nesting, and getting a long draw off the tool.
Containers
Deep tubs and long cores.
ContainersSeed trays
Deep cells and denesting.
Seed traysNozzles
Orifices that shape a stream.
NozzlesCaps
Parts that sit on a neck.
CapsEjection design
Pushing a deep part off a core.
Ejection designDrag marks
Scuffs from a long pull.
Drag marksPolypropylene
A common funnel resin.
PolypropyleneIndustrial and transportation
How we support industrial programs.
Industrial and transportationMolded parts hub
Every part-type guide, grouped by family.
Molded parts hubFAQ
Questions about molded funnels
Why does our funnel glug and spit?
The stem is sealing the container, so air has to come back up the same path the liquid uses. A channel molded up the inside of the cone gives the air its own route and the flow becomes steady. A quick pour test with the real liquid into the real container is the fastest way to confirm the channel works.
Why is the stem thicker on one side?
The long core pin that forms it is pushed sideways by the melt. Supporting the pin at its far end, or shortening the stem, brings it back to center. Nesting steps also let air between stacked funnels, so a stack comes apart without pulling a vacuum.
Why are there scuff marks inside the cone?
The cone grips the core as it shrinks and drags on the way out. More taper, a polish along the pull direction, and ejection spread around the rim clear it up.
Can funnels be stacked for shipping?
Yes, with small steps on the outside of the cone. Without them, identical cones nest so tightly that they stick together and have to be pulled apart.
Next step
Quote a funnel with its use in mind
Upload the funnel, or tell us the sizes. DFM feedback covers taper for the draw, stem support, the air channel, and nesting.