A variety of power saws, either table mounted or portable can be used to saw PALSUN. Shearing or punching are also possible.
Laser or water-jet cutting are less common but also possible techniques:
1. Table Mounted or Portable Circular Saws
These types of saw are widely used to saw PALSUN.
There are two major workshop types and one portable type:
- A Moving Table, Fixed Blade Bench Saw: is preferable for long, straight sawing.
- Radial Arm Saw: is generally used for “cross-cut” (width) or diagonal sawing.
- Portable
Circular Saw: usually restricted for use on site for straight cutting,
is slower and not as accurate as table saws. This type of saw may be
attached underneath a special bench to function as an on-site, limited
operation fixed table saw.
Circular Saw Blades:
Should
be fine toothed hollow ground, or preferably carbide tipped, triple
chipped (Alt 1 on next page) or alternate bevels (Alt 2 on next page),
with minimal blade body contact with the cut material. Such blades can
offer clean, good quality cut.
a. Table 9: Generally Accepted Recommendations for Circular Blade Specifications:
No. |
Property |
Value |
1 |
Clearence angle α |
10-20° |
2 |
Rake angle γ |
5-15° |
3 |
Alternate double-bevel angle (Alt. 1) α°
Alternate bevel angle (Alt. 2) β° |
45°
10-15° |
4 |
Cutting speed (m/min.)
(ft./min.) |
1,000-3,000
3,300-10,000 |
5 |
Rate of feed (m/min.)
(ft./min.) |
30
11/4 |
6 |
Thin guage: (1.5-2.5mm) Tooth pitch t (mm)
(1/16"-3/32")
Teeth per in.) |
2.5-6.0
10-12 |
7 |
Heavy guage: (3.2-12mm) Tooth pitch t (mm)
(1/8"-1/2") Teeth per in.) |
6.5-8.5
3-4 |
Notes:
1. 2 Possible alternatives (Alt 1, Alt 2 see next page) are supplied by
different tools manufacturers as alternate beveled teeth for blades
intended for cutting plastics, and both offer satisfactory cuts (line 3
in the table).
2. For sawing thin gauge sheets of less than 2mm thickness, It is recommended to batch together 10 - 15 such sheets, with a
thicker (3-4mm) bottom sheet for support.
3. Shearing is a preferable option for cutting a single thin gauge sheet.
b. PALRAM Particular Circular Saw Cutting Recommendations:
These
recommendations are based on technical know-how, particular tests and
vast practical experience accumulated during years of work. These
recommendations are to be accepted only as general guidelines.
Table 10: Saw Blade Specifications for Cutting PALSUN
up to 5mm Thickness
| Diameter (mm / in.) |
300 / 12 |
| No. of teeth in blade |
96 |
| Thickness (mm / in.) |
2.2 - 3.2 / 3/32 –1/8 |
| Teeth angles |
Rake- 10°, clearance 15° |
Tooth appearance
|
Alternating: Left–right  |
| Speed |
1800 – 2400 rpm |
Table 11: Saw Blade Specifications for Cutting PALSUN
6 to 12 mm Thickness
| Diameter (mm / in.) |
350 / 14 |
| No. of teeth in blade |
108 |
| Thickness (mm / in.) |
2.2 - 3.2 / 3/32 –1/8 |
| Teeth angles |
Rake- 10°, clearance 15° |
Tooth appearance
|
Alternating:  |
| Speed |
1800 – 2400 rpm |
Notes:
1. Teeth shapes sketches are not to scale. They should be considered to serve only as an indication.
2. The PALSUN should be placed on a firm flat base and clamped into position during sawing.
3. When sawing PALSUN it is recommended to leave the protective PE film on.
4. If the cut sheet vibrates during sawing, cardboard sheet padding may be placed beneath it to absorb the vibrations.
5.
When sawing thin gauge palsun it is recommended not to cut single
sheets by themselves, but saw a pack of 5-10 sheets at the time,
clamped firmly together to a steady base.
6. Low to moderate feed rate should be used when the sheets approach the blad, or vice versa. A feed rate that is too high
can cause gumming, splitting or breaking of the sheet edges.
2. Band Saws
Band
saws can be used for cutting PALSUN sheets of most thicknesses with
acceptable results. Band saws are workshop tools. In PALSUN fabrication
they are mostly used to cut formed parts or irregular shapes. It is
possible to cut flat sheets in straight lines too, but in limited
length and width, due to the tool’s limitations. Thin gauge sheets are
better sawed when stacked to a thickness of 10 -12 mm (0.4 - 0.5 in.)
The preferred band saw blade should have slightly set teeth, with 10 –
20 mm (0.4 - 0.8 in.) blade widths.
Table 12: Recommended Band Saw blade Properties
No. |
Property |
Value |
1 |
Clearence angle α |
10-20° |
2 |
Rake angle γ |
5-15° |
4 |
Cutting speed (m/min.)
(ft./min.) |
1,000-6,000
1,950-3,300 |
5 |
Rate of feed (m/min.)
(ft./min.) |
20
13/16 |
6 |
Thin guage: (1.5-2.5mm) Tooth pitch t (mm)
(1/16"-3/32") (Teeth
per in.) |
1.5-2.0
12-18 |
7 |
Heavy guage: (3.2-12mm) Tooth pitch t (mm)
(1/8"-1/2")
(Teeth per in.) |
2.5-3.5
7-10 |
Notes:
1. A band saw is suitable for cutting curved lines and 3-dimensional, formed parts.
2. For cutting a few formed objects of the same shape, they must be firmly clamped together.
3. A band saw cutting usually yields rougher finished edge, which must be smoothed by sanding and polishing.
An endless belt sander is a preferred tool for such an operation.
4. We recommend using a circular saw for better-finished edges, whenever possible.
3. Portables: Jigsaw or Saber Saw
Portable
saws of these similar types use short movement, reciprocating blades,
instead of one-direction orientation, continuous movement blades like
those of circular or band saws, and are much slower in operation.
- Jigsaw or saber saws are usually used on site, for limited cuts of irregular shape, or relatively short, straight lines.
- Jigsaw
or saber saw blades are usually made of high-speed steel, with slightly
set teeth. Specially designated blades, intended for rigid plastics,
with alternate beveled teeth, are available.
- A
slow feed rate (speed depends on sheet thickness) of about 1.5 mm/sec.
and maximal reciprocating speed (about 800 oscillations/min.), yields
acceptable results for smoothness of cut.
- Due
to the reciprocating blade movement, it is necessary to clamp the sheet
down firmly when cutting, to steady it during saw operation.
- Thin
gauge sheets are better sawed stacked together to a total thickness of
10-12 mm (0.4 - 0.5 in.), with the pack clampe down firmly to steady it
during sawing.
- Jigsaw or
saber saw cutting usually result in inferior finish of the cut edges,
worse than the results achieved by a circular saw. We recommend that
sanding and polishing of the cut edges should be used as a regular
practice. An endless belt sander is the preferred tool for such an
operation.
4. Sawing Tips
Chipping and gumming are among the most common problems when sawing.
- Chipping: Various sized chips are broken of on both edges of the sawing line, leaving the cut edges rough and uneven.
- Gumming: Chips and splinters from the advancing saw blade overheat during the
sawing process, melt and create heaps of cooled down material in front
of the blade and on both sides of the cut. The swarf sticks to the
edges leaving an ugly, rough edge finish, difficult to clean.
Gummed material may also stick to the blade itself and cause seizure.
The
same uncontrolled heat that creates gumming, may also induce undue
internal stresses along the edges of the cut, necessitating annealing
of the sheet.
Recommended Remedies:
- Choose the correct tooth size and pitch.
- Select a more appropriate saw speed.
- Lower the feed rate.
- Examine the sharpness of the blade.
- Examine the blade alignment.
- Cool the blade with compressed air when long cuts are required.
- Take frequent pauses during long production runs, to let the saw blade cool down.
- Begin sawing with the blade already running at the full recommended speed.
5. Finishing Recommendations for Well Done Sawing and Cutting
Unintended
saw marks, rough or jagged corners, or uneven, drawn edges created by
imperfect shearing may result in crazing and cracking, that can develop
further to failure under load.
We recommend finishing the edges of cut PALSUN sheets (or all types of plastics) by finishing the edges to a smooth appearance.
This will ensure that no cracks will develop from the irregularities at the edges.
Smoothing techniques are discussed in Section VII (page 23).
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