Session: 

Paper Number: 142448

142448 - Temperature and Force While Forming A1100 Round Solid Cylinders in a Friction Stir Extrusion Machine 

There is increasing interest in friction stir extrusion (FSE) to form solid cylinders and hollow cylinders or tubes from solid billets, metal chips, and powders. This is because friction stir forward extrusion (FSFE) and friction stir back extrusion (FSBE) can impart unique material properties to work pieces, reduce energy consumption compared to other processes, be used to recycle waste such as metal chips due to machining, and produce parts through additive manufacturing by stirring powders.

Both FSFE and FSBE are commonly referred to as friction stir extrusion. Friction stir forward extrusion consists of a billet, material chips, or power inside a cylindrical die cavity. A rotating probe with the same diameter as the die cavity but has a hollow shaft running the length of the probe contacts the material that is extruded. The friction between the rotating probe and the material, such as a billet, heats the billet and softens it while at the same time the rotating probe results in severe plastic deformations that result in ultrafine grains in the extruded cylinder. If recycling chips from machining are stirred, lower energy requirements compared to compacting are required and a solid cylinder is formed, thus this process is attractive to machining shops that produce aluminum and magnesium products.

For friction stir back extrusion, the material, such as a billet of aluminum is placed inside a die. A rotating probe with diameter smaller than the billet diameter is forced against the billet and heats the billet up so that a reduced force can be used to form a tube after the rotating probe is retracted from the tooling. Previous researchers have investigated the flow of solid aluminum and magnesium into a hollow rotating probe that is pressed against the billet.

This paper will present results of an operational custom-built friction stir extrusion machine that is highly instrumented with respect to force, vibration, temperature, and displacement control. For this paper an A1100-o aluminum billet undergoes FSFE at various plunge rates and rotating probe speeds using a design of experiments approach in order to explore the relationship between these parameters and the resulting plunge force and temperature at the billet. Force was measured using S-shaped force transducers, while the temperature was measured using a thermocouple and compared to a handheld non-contact infrared thermometer aimed at the rotating probe at the tip of the die and temperature from an infrared camera. These temperature results were then compared to a heat transfer model to estimate the temperature and heat generated at the point of contact where the rotating probe and billet are in contact.

Force data has non-EMI generated noise that may be due to vibration from support structures. However, this has not been ascertained. The force data decreases with time while the temperature at the thermocouple decreases, which indicates that the heat generated due to friction continues to soften the billet. Force and temperature data will be evaluated as a function of time and of the probes plunge into the billet.

Surface quality of the extruded material is evaluated and recommendations and conclusions are presented.

Presenting Author: William Emblom Emblom Engineering

Presenting Author Biography: William Emblom performs engineering desgn, analysis, and test for manufacturing systems and concentrates on material deformation processes and controls. When not consulting, he teaches engineering mechanics, machine design, manufacturing processes, and capstone classes at a local university.

Authors:

William Emblom Emblom Engineering
Jhonatan Gil Romero Univ of Lousiana at Lafayette
Gabriel Dimonde Univ of Louisiana at Lafayette
Alaric Bloss Univ of Louisiana at Lafayette
Grahm Casse Univ of Louisiana at Lafayette
Paul Daugereau Univ of Louisiana at Lafayette
Jacob Garcia Univ of Louisiana at Lafayette
Javen Bolden Univ of Loiuisiana at Lafayette
Scott Wagner Michigan Tech
Vinh Nguyen Michigan Technological University
Paul Darby Univ of Louisiana at Lafayette