Analysis of the manual work
A good understanding of the manual work is
needed as a background to automating the corresponding
task — floor tiling in the present case.
Consequently, this section will specify the performance
requirements from the tiling operation; describe
the manual work methods, including the tools
needed for them; and give the work inputs, as measured
in a field study.
Navon w8x analyzed two floor tiling technologies,
showing that only one can realistically be robotized.
That technology involves ceramic tiles which are set
directly on the concrete slab — the latter being cast
with self-leveling concrete to an accuracy of "0.1%.
A field study was conducted to investigate the
manual process thoroughly. The study included ob-
servations and work sampling the methodology for
both is described in Ref. w9x. to measure the work
inputs in the manual work. Tiling must satisfy the
following performance requirements:
¯ The tiles must be set in straight parallel lines.
¯ The distances between neighboring tiles must be
uniform about 5 mm..
¯ Neighboring tiles have to be on the same level.
¯ The glue has to be spread uniformly over the
entire back of the tile.
¯ The tile must be pressed evenly against the floor.
The manual operation involves three stages: i.
preparatory work, ii. tile setting proper, and iii.
additional tasks. The preparations include cleaning
the working surface; checking that it is dry and
smooth; preparation of tiles and tools at a close and
convenient location; and preparation of the glue. The
tile setting itself comprises four sub-stages:
1. Applying a uniform layer of glue on the floor
with a special spatula to be described below..
Normally, the glue is spread over a strip having
an area of 1.5–2 m2.
2. Picking up a tile and checking that it is not
cracked, chipped, stained, or otherwise defective.
3. Laying the tile in a straight line and adding plastic
spacers cross-sectioned. to keep to the prescribed
distance from previously laid tiles.
4. Pressing the tile against the floor and leveling it.
The additional tasks include joint filling, and fitting
partial tiles for the last row near the wall. The
latter tasks involve measuring the exact gap between
the last row and the wall, cutting each tile accordingly,
and setting it.
The tools used in the manual work include the
following.
¯ A container for the preparation and keeping of
the glue.
¯ A set of spatulas — one regular and one
dented. The dented spatula is used to apply the glue
on the floor in ‘‘rows’’, the purpose of which is to
allow leveling of the tile by pressing it against the
floor and excess glue from the ‘‘rows’’ to be
squeezed into the gaps between them. The size of the
dents is 5=5–10=10 mm, depending on the size
of the tile and the leveling accuracy of the concrete
floor.
¯ A rubber ‘‘hammer’’ for pressing the tile onto
the layer of glue.
¯ Measuring tools: a tape measure and a spirit
level.
¯ Cutting and grinding tools: a guillotine, an
electric saw, and a grinding machine.
The work inputs of the manual work vary according
to the size of the tiles, the size and shape of the
rooms, etc. Therefore synthetic work inputs were
measured, i.e., the durations for each sub activity
were measured separately. This enabled a detailed
analysis of the work inputs for various sizes of tiles
and different rooms. The resulting work inputs of the
manual work vary from 0.47 hrm2 for a 3.00=
4.00-m room and tiles of size 20=20 cm, to 1.42
hrm2 for a 2.60=2.60-m room and tiles of size
10=20 cm.