Manufacturing-process-headstones

The Manufacturing Process

The first step is to choose the type (typically marble or granite) and color of the stone. The granite
block is then cut from the bedrock. There are three ways of doing this. The first method is drilling. This
method uses a pneumatic drill that bores vertical holes 1 in (2.54 cm) apart and 20 ft (6.1 m) deep into
the granite. The quarrymen then use 4 in (10.1 cm) long steel bits that have steel teeth to cut away at
the core of the rock.

Jet piercing is much faster than drilling, about seven times so. In this method, 16 ft (4.9 m) can be
quarried in one hour. The process uses a rocket motor with a hollow steel shaft to expel a blend of
pressurized hydrocarbon fuel and air in the form of a 2,800°F (1,537.8°C) flame. This
flame is five times the speed of sound and cuts 4 in (10.2 cm) into the granite.

The third way is the most efficient method, quieter, and produces almost no waste. Water jet piercing
employs water pressure to cut the granite. There are two systems of water jet piercing, low pressure
and high pressure. Both emit two streams of water, but the low pressure system streams are under
1,400-1,800 psi, and the high pressure streams are under 40,000 psi.

The next step is to remove the block from the quarry bed. Workers take large pneumatic drills tipped
with 1.5-1.88 in (3.81-4.78 cm) steel bits tipped with carbide and drill horizontally into the block of
granite. They then place paper-wrapped blasting charges into the holes. Once the charges are set,
the block makes a clean break from the rest of the rock.

Granite blocks are usually about 3 ft (0.9 m) wide, 3 ft (0.9 m) high, and 10 ft (3 m) long, weighing
about 20,250 lb (9,185 kg). Workers either loop a cable around the block or drill hooks into either end
and attach the cable to the hooks. In both ways the cable is attached to a large derrick that lifts the
granite block up and onto a flatbed truck that transports it to the headstone manufacturer. The
quarries tend to be independently owned and sell the granite to manufacturers, but there are some
larger companies that own quarries. After arriving at the manufacturing house, the granite slabs are
unloaded onto a conveyor belt where they are cut into smaller slabs. The slabs are generally 6, 8, 10,
or 12 in (15.2, 20.3, 25, and 30.4 cm, respectively) thick. This step is done with a rotary diamond saw.
The saw is equipped with a 5 ft (1.5 m) or 11.6 ft (3.54 m) solid steel diamond blade. The blade usually
has about 140-160 industrial diamond segments and has the ability to cut an average of 23-25 ft 2
(2.1-2.3 m 2 ) an hour. The cut slabs are passed under a varying number of rotating heads (usually
eight to 13) with differing levels of grit arranged The manufacturing of a headstone. from the most
abrasive to the least. The first few heads have a harsh diamond grit, the middle heads are for honing,
and the last few heads are equipped with felt buffer pads. These pads have water and aluminum or tin
oxide powder on them to polish the stone to a smooth, glossy finish. The polished slab is then moved
along the conveyor belt to the hydraulic breaker. The breaker is equipped with carbide teeth that exert
close to 5,000 psi of hydraulic pressure on the granite slab, making a vertical cut through the stone.
The cut stone is then fashioned into the appropriate shape. This is either done by hand with a chisel
and hammer, or more precisely with a multi-blade diamond saw. This machine can be set to hold up to
30 blades, but usually is only loaded with eight or nine. Equipped with nine blades, this multi-bladed
diamond saw can cut 27 ft 2 (2.5 m 2 ) an hour. The surfaces of the stone are then polished again. In
a highly automated process, 64 pieces can be polished at a time. The vertical edges are polished by
an automated polishing machine, similar to the surface polisher. This machine chooses the harshest
grit head and works it across the vertical edges of the stone. The machine then works its way through
the other grits until the edges are smooth. The radial edges are ground and polished at the same time
using two diamond grinding drums. One has a harsh grit diamond, and the second has a finer grit. The
stone's radial edges are then polished. If intricate stone shapes are needed, the polished
stone is moved to the diamond wire saw. The operator adjusts the saw and starts the process, which
uses computer software to etch the shapes into the headstone. Any fine etching or detailing is finished
by hand. The headstone is then ready for finishing. Rock Pitching entails chiseling the outer edges of
the stone by hand, giving a more defined, personal shape. Now that the headstone is polished O and
shaped, it is time for the engraving. Sandblasting is generally used. A liquid glue is applied to the
headstone. A rubber stencil is applied over the glue and then covered with a carbon-backed layout of
the design. The carbon transfers the design prepared by the draftsman, onto the rubber stencil. The
worker then cuts out the letters and design features that are wanted on the stone, exposing them to
the sandblasting. The sandblasting is either manually done or automated. Either method is done in an
enclosed area due to the dangers of the process. The worker is entirely covered to be protected from
the grains reflected off the stone. The course cutting abrasive is exerted at a force of 100 psi. Dust
collectors collect and save the dust for reuse. The stone is then sprayed with high pressure steam to
get rid of any leftover stencil or glue. It is again polished and closely inspected, then packaged in
cellophane or heavy paper to protect the finish.