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ManualsBrandsPlexiglas ManualsAcrylic Sheets0.080 in. x 24 in. x 24 in. Clear Acrylic Sheet (8-Pack)

ANNEALING PLEXIGLAS

Health and Safety Precautions

Annealing Plexiglas

acrylic sheet should not result in the

release of harmful concentrations of vapors or gases under the

annealing conditions recommended in this manual. However,

Plexiglas

acrylic sheet may release high concentrations of vapors

and monomers if heated to temperatures in excess of 350°F

without adequate ventilation.

The annealing oven should have forced-circulation and should

have bleed and makeup vents, so that the air is changed at least

twice an hour to remove fumes and cement-solvent vapors. Fumes

and cement-solvent vapors should be exhausted to the outdoors.

Parts should be heated to and held at the recommended annealing

temperatures for the recommended times (see Table 6).

Plexiglas

acrylic sheet is a combustible thermoplastic material.

Observe fire precautions appropriate for comparable forms of wood

and paper products.

Annealing

Proper annealing is one of the most effective single measures

that can be taken to insure good service from parts made of

Plexiglas

acrylic sheet.

Annealing consists of prolonged heating of the acrylic part at

temperatures lower than those used for forming, followed by

slow cooling. Internal stresses set up during fabrication of the

article are reduced or eliminated by this treatment. All edges

should be cut or machined with as little internal stress as possible.

If excessive internal stress is present in the parts to be cemented,

crazing will occur during the cementing process. It may be

necessary to anneal the parts to reduce internal stresses set up

in the parts during fabrication or thermoforming operations.

Annealing results in greater dimensional stability and greater

resistance to crazing. Heat treating also improves the strength

of certain cemented joints.

To obtain the benefits of annealing, the Plexiglas

acrylic

sheet parts must be annealed after all fabrication steps, including

polishing, are completed. In addition to annealing after final

finishing, machined parts should be annealed before cementing

to reduce stress due to machining in the cement joint area.

Determination of Best Annealing Temperature

The optimum temperature for annealing any specific part can

best be determined by experimenting with a few samples to find

the maximum temperature at which the part can be heated for

the times indicated in Table 6 without objectionable deformation.

Parts should be annealed at as high a temperature as possible.

Annealing at temperatures lower than those listed in Table 6,

below, will not give effective relief and redistribution of stresses.

Machined Plexiglas

acrylic sheet parts that have not been heated

to forming temperature should be annealed with caution in the

higher temperature ranges.

The annealing temperature should be approximately 10°F

below the minimum temperature at which the part shows

deformation of one percent. A greater change indicates that the

part has not been properly formed. The fabrication process

should be carefully reviewed and revised until the parts will

withstand these annealing temperatures. Particular attention

should be given to forming temperatures and conditions because parts

Recommended Annealing Times and Temperatures for Plexiglas

Acrylic Sheet

Maximum Thickness

(Inches)

0.060 to 0.177

0.236 to 0.354

0.472 to 0.708

0.944

1.500 to 1.750

2.0

Time* (Hours) to

Heat Mid-Plane

⁄

221

(105

⁄

* The time required to raise the temperature of the mid-plane to a temperature equal to room temperature plus 99% of the difference between room temperature and annealing temperature.

Notes: (1) Anneal parts at the highest temperature for indicated time. If distortion occurs, try the next lowest temperature.

(2) The cycles given will be satisfactory for most formed parts. For extreme forming, such as 100% biaxial stretching, use lower temperatures.

(3) Air should circulate around each part.

230

(110

⁄

Heating Time (Hours) in Forced-Circulation Air Ovens Maintained at the Indicated

emperature for P

arts Made of Plexiglas

G and MC Acrylic Sheet

212

(100

⁄

203

(95

⁄

TABLE 6

ACRYLIC SHEET