A screw lotion pump, also known as a twist lotion pump, functions through a combination of mechanical and suction-based mechanisms to dispense cosmetics or liquid soap. Here's how it typically works:

Twisting Action: The user twists or rotates the pump head or collar, usually in a clockwise direction, which engages the mechanism inside the pump.

Unlocking the Pump: This twisting action unlocks the pump mechanism, allowing it to operate.

Screw Mechanism: Inside the pump assembly, there is a screw or helix mechanism connected to the pump piston or plunger.

Creating Suction: As the user continues to twist the pump head, the screw mechanism moves downwards, creating suction within the pump chamber.

Drawing Product: The suction draws the product, whether it's lotion, liquid soap, or another cosmetic fluid, up through the dip tube and into the pump chamber.

Dispensing: Once the pump chamber is filled with the desired amount of product, the user presses down on the pump head. This action compresses the pump piston or plunger, forcing the product out through the nozzle or dispenser opening.

Sealing Mechanism: After dispensing, releasing pressure on the pump head causes the piston or plunger to return to its original position. At the same time, a sealing mechanism prevents the product from leaking or dripping out of the pump.

Locking the Pump: To prevent accidental dispensing or leakage, the user can twist the pump head back in the opposite direction, locking the pump mechanism in place until it's ready to be used again.

Overall, the screw lotion pump relies on the rotational motion of the pump head to engage a screw mechanism, creating suction to draw the product into the pump chamber, and then dispenses it through pressure applied by the user. This design provides controlled and hygienic dispensing of cosmetics or liquid soap products.