The mechanical behavior of thermoplastic materials in the deep drawing process

Abstract

This study presents a mechanical analysis of the deep drawing of thermoplastics in the glassy state. A theoretical stress analysis is conducted by applying principles of classical plasticity together with several assumptions. A simple model is presented relating drawing performance with the mechanical properties of the plastic measured under the conditions of the fabrication operation. An experimental procedure is described for evaluating the drawability of a plastic. Data on thirteen thermoplastics are used to demonstrate the applicability of the theory developed.

Experimental study on cold press workability of aluminum‐polyethylene sandwich laminates

“…A conical die of 60" taper (1) angle without holding force, shown in Fig. 1, is used preferably in a deep drawing test, rather than a flat die (15) with holding force at the die lip zone. The conical die arrangement with the detailed dimensions of Table 2, is recommended due to the absence of wrinkling at the circumferential edge of the blank.…”

A numerical study on warm deep drawing of polypropylene

“…Deep drawing is a well-established metal forming process [1] and is widely used with steels, aluminum alloys, and other metals in the automotive as well as nonautomotive industries. Even though several articles have been published on deep drawing of polymers, [2][3][4][5][6][7] it has not found widespread application in the plastics industry. One of the common manufacturing processes in the plastics industry is called thermoforming in which a preheated thin plastic sheet is placed on a mold and vacuum formed into the shape of the mold.…”

“…[ 2–7 ] In these studies, the emphasis was more on the relationship of deep drawability with material parameters and not with process parameters. In addition to several amorphous polymers, Evans [ 3 ] performed cup drawing tests on PP at 23°C and observed failure by necking in the cup wall. Machida and Lee [ 7 ] reported experimental results on the cup drawing of propylene‐ethylene copolymer under isothermal and differential heating conditions at temperatures up to 130°C.…”

“…During the past several years, polypropylene (PP) has found an increasing number of applications in automotive components such as instrument panels and housings, and in household products, such as containers. The reasons for selecting PP in many such applications can be attributed to its low density of 0.9 g/cm 3 , relatively low cost, and a balance of mechanical properties. In addition to weight and cost savings, other qualities offered by PP are very low water absorption, good chemical resistance, high food safety, and low electrical conductivity.…”

The deep drawing of thermoplastics

“…The aims of doing this have either been the development of directional mechanical properties in the product, or an increase in fabrication rates. A number of papers have considered the performance of thermoplastics in the simple process of the deep drawing of cups from sheet (1)(2)(3)(4)(5). Comparisons of the observed performance with theory have been made in terms ofparaineters found to be relevant for metals.…”