Is a solid part being made simply from the application of pressure and not from melting?

https://www.youtube.com/shorts/4flmQbopeBs

This is "sintering":

https://en.wikipedia.org/wiki/Sintering

A powdered metal alloy is first compressed to shape, then heated in a sintering oven to a bonding temperature. This method of production allows for self lubricating materials and various alloy-formed parts that can not be produced by other methods.

Sintering compresses metal powder into a solid shape. It is heated to a "bonding" temperature below the temperature where the metal totally melts.

Widely used (before high performance plastics) as bushings in home appliances (Fans, Air Conditioners, Washing Machines, Clothes Dryers, etc.) and automobiles. The final bonded metal is like a sponge and can be saturated with oil. Easier to make than solid metal bushings and normally does not need an external oil supply (oil cups, grease fittings, etc) for the limited lifetime of a home appliance.

Most 20th century Automotive starter motors used sintered bronze bushings to support the motor shaft. Inexpensive, "permanently lubricated", and could last 5-10 years. You can purchase oil impregnated bronze bar stock to make custom sized bushing to restore many old starter motors, fan motors, etc. Automotive generators and alternators usually used ball bearings since they rotated the whole time an engine was running.

Cheaper than ball bearings and not regularly used for "Heavy Industrial" applications.

Mostly Bronze metals.

Not used for structural members.

https://oilite.com/oilite

Comes in "Food Safe" versions (with mineral oil), "Marine" versions (impervious to salt water) and lots of other specialty versions. There are now "impregnated" plastic materials that combine PTFE and Bronze powders to make bushings that perform very much like a solid metal bushing.

As someone commented at that site, this is NOT forging. Forging raises the temperature of a metal above it's "plastic" temperature and compresses the metal together to make it denser and stronger.

The press used for sintering compacts metal powder grains closer together so they will "fuse" when heated to a temperature below the plastic state of the metal. Like warming up wax beads and pressing them together to make a wax sponge material.

Sintering can also be used to make porous metal fuel filters for car and truck engines.

An example you may be familiar with: Lionel wheels were sintered steel.

I have a large sintered brass or bronze filter in my oddball object stash. I was told by the non-railroader previous owner that it was for a steam engine of some kind. Dunno if that's true as I have no clue if steamers had water filters. It wouldn't seem like a good idea if it clogged. I'll post a photo if anyone is interested.

Sintered bronze bushings were developed by Chrysler in 1930 under the Oilite brand name.

One place I've come across sintered steel was in padlocks.