Exploratory tests on machining and related properties of fifteen tropical American hardwoods

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Title:
Exploratory tests on machining and related properties of fifteen tropical American hardwoods
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Davis, E. M
Forest Products Laboratory (U.S.)
University of Wisconsin
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U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory ( Madison, Wis )
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[EXPLOUIATOIY TESTS ON AtACEHININ(

ANID I[LATED PIROPEIRTI[S OC FIFTETN
TIPPICAL AMEIICAN IAIRDWOOUS
April 1949


No. P1744


UNITED STATES DEPARTMENT OF AGRICULTURE
FOREST SERVICE
FOREST PRODUCTS LABORATORY
Madison 5, Wisconsin
In Cooperation with the University oi Wisconsin


* -"n


]















Digitized by the Internet Archive
in 2013









http://archive.org/detailIs/rytests00fore




-XPLORATORY TESTS ON IA?7.I ':;:: AJD RELATED PROPERTIES OF

FIFTL:Ji TROPICAL A.ERICAN HARD'.OODS


By

E. 1. DAVIS, Technologist
Forest Products Laboratory,-- Forest Service
U. S. Department of Agriculture





Introduction


The Forest Products Laboratory is increasingly receiving requests from
American importers and manufacturers for information on tropical American
hardwoods. The objectives of the work here reported were to obtain information
on the machining and related properties of fifteen of these woods for compari-
son with native hardwoods and to determine to what extent the tests that have
already been developed for native hardwoods are applicable to tropical species.

The machining properties that were investigated were planing, shaping, turn-
ing, sanding, boring and mortising. The related properties of specific
gravity, cross grain, and shrinkage were also investigated because of their
relation to the general utility of the woods.


Test h'aterial


In most of the species ten or more samples were available for test. Exhaustive
tests would require more material but this amount suffices to give good indi-
cations of machining and related properties. The fifteen woods, which are
listed below, all came from Central Amnerica or northern South America except
coigue, which came from Chile. They, of course, do not represent all of the
tropical hardwoods but are all species on which the Forest Products Laboratory
has received requests for information on one or more of the properties inves-
tigated.

Scientific Name e

Anacardium sp. Espavel
Brosimum alicastrum group Ujuste
Calophyllum brasiliense Santa iLaria
Carapa guianensis Crabwood
(cedro macho, andiroba)
-1.-aintained at :iT'ison 5, xis. in cooperation with University of '.isconsin.


Report No. R1744


-I-




Scientific Name Name

Cordia alliodora group Laurel
Dialyanthera sp. Cuangare
Enterolobium cyclocarpum Jenezero
(Guanacaste)
Hieronyma alchorneoides Pilon
Nectandra sp. Chachajillo
Nothofagus sp. Coigue
Prioria copaifera Cativo
Symphonia globulifera :Lapelo
Virola sp. Banak
Vochysia hondurensis San Juan
Zanthoxylum sp. Prickly yellow

A very confused situation exists concerning the common names of tropical
American hardwoods. The same species often goes by different common names in
different regions, and the same common name is sometimes applied to different
species in different regions. In general the common names used above are those
designated by the shippers and are names in common use. To insure identifying
the woods beyond possibility of misunderstanding, the botanical names are used
in all the tables of this report.


Test Procedure


The same general test procedure was followed as that described in detail in
U. S. Depte Agr. Tech. Bull. 824, "Machining and Related Characteristics of
Southern Hardwoods." It was not practical to make all of the tests described
in that bulletin, however, nor to do as much work on the effect of machining
variables.

Aill test material was dried to 6 percent moisture content.


Machining Tests


Planing

Samples were planed at 3,600 r.p.m. at feeds of 29 and 58 f.p.mo using a 300
cutting angle. The results, which are shown in table 1, show both the planing
quality of the woods and the occurrence of planing defects.

Comparison of the planing properties of the tropical hardwoods is based on the
percentage of defect-free pieces and varies from 15 percent to 90 percent for
different species. This compares with a range of 21 percent to 91 percent for
witive hardwoods and gives a good indication of the amount of sanding that may
be required to prepare the woods for any fine finish.


Report No. R1744


-2-




The kinds of planing defects and their frequency of occurrence are also shown.
For any given defect the occurrence may range from none up to very common in
different woods.


Shaping

Tests were made on a two spindle shaper operating at 7,200 r.p.m., and cuts
were made at angles that varied from parallel to grain to right angles.

The shaping properties of the woods tested, taking all defects into account,
are shown in table 2. The percentage of good to excellent pieces varies in
different species from 28 percent to 67 percent. This is a better showing
than was made by native hardwoods, which ranged from 3 percent up to 62 per-
cent. This difference is chiefly due to the larger proportion (among native
hardwoods) of light woods that are soft and shape poorly.

Rough cutting on end grain was the most common shaping trouble as with native
hardwoods. In most species it was the sort of superficial roughness that
sands off without too much trouble, but in some of the lighter woods small
tearouts sometimes occurred.


Turning

Turnings of uniform size and pattern were made on a modified back-knife lathe
after which they were carefully examined for defects and graded for quality.
Results are shovn in table 3.

Quality comparison is based on the percentage of good to excellent turnings
that were obtained. This varied from 40 percent to 90 percent in different
tropical woods as compared with a range of 58 percent to 91 percent for 25
native hardwoods.

Surface roughness was the most common defect encountered but it can usually be
removed by a little sanding. Detail refers to corners and edges that are
damaged instead of being sharp and clear cut. A wood may, however, be somewhat
poor in detail, but still satisfactory for turnings of sorts that do not
require sharp detail. Tearouts, as the name indicates, are spots where bits"
of wood have torn out in turning. These are rare except in light soft woods,
and in cuts approaching right angles to the grain.


Sanding

A small drum sander with garnet abrasive in the 1/0 and 3/0 grit sizes was
used. After sanding the samples were examined for scratches and fuzziness and
comparison of species was based on the percentage of samples in each wood that
was free from these defects. Results are given in table 4.

Only one of the woods, coigue, had pores too fine to be seen with the naked
eye and most of them had pores so coarse that they tended to obscure fine


Report No. R1744


-3-




scratches. This accounts for the fact that 13 of the 16 woods showed 80 per-
cent or more of scratch free pieces when sanded with 1/0 grit. None of the
woods showed visible scratches when 3/0 grit was used.

As a rule, fuzzing was more prevalent than scratching in sanding these tropical
hardwoods. Although fuzzing is greatly reduced when 3/0 grit is used, most of
the woods still developed some fuzzy pieces.


Boring

Two holes were bored in each sample with a small boring machine using a stand-
ard type one inch bit*

The holes were graded for smoothness of cut and measured with a plug gage for
variation from the size of the bit or off size (see table 5) Percent of good
to excellent holes (as far as smoothness was concerned) varied from 40 up to
100 as compared with a range of 62 to 100 for 25 native hardwoods.

The range in off size or variation from the size of the bit is practically
identical with that in 25 native hardwoods.


Mortising

Two mortises were cut in each sample using a hollow chisel mortiser of the half
inch size. The holes were graded for smoothness of cut and for variation from
the size of the hollow chisel.

Tropical hardwoods like native ones vary widely in mortising properties and
this comparison is shown in table 6. The proportion of fair to excellent
mortises based on smoothness of cut ranged from 11 to 100 or about the same as
for native hardwoods. The amount of offsize of the mortises (or variation
from the size of the chisel) was from 0.0027 to 0.0077 or somewhat more than
in native hardwoods on the average.


Related Properties


Specific Gravity

Specific gravity of the woods tested (based on oven-dry-weight and green
volume) is given in table 7. The lightest wood, virola, is practically the
same as basswood in this respect and the heaviest, pilon, is slightly heavier
than hickory. Specific gravity yields a good clue not only to strength
properties but to power consumption and rate of dulling of tools in machining.


Cross Grain

The presence of spiral grain was determined by splitting small samples and
making measurements. The average slope of spiral grain ranged from 2*5


Report No. R1744


-4-




percent to 8.3 percent in different woods or about the same as for native
hardwoods (table 8).

Presence of interlocked grain was determined by examination and splitting but
accurate measurement was not practical, This is a more extreme type of cross
grain. Two-thirds of our native hardwoods have little if any interlocked
grain, but 11 of 15 tropical hardwoods had more or less of it including four
species in which every piece had interlocked grain.

Flat sawed boards with interlocked grain sometimes twist in drying while quarter
sawed boards with the same type of grain not only season much better but often
show an attractive ribbon stripe figure.


Shrinkage


Shrinkage from green to 6 percent moisture content is shown in table 9. In
all woods tangential material was available for test, and radial material also
was available in 8 woods. In general the shrinkage was about the same as for
native hardwoods both in spread between species and in maximum and minimum
species. Shrinkage is directly related to warping tendencies and hence to
abilityy to stay in place."


Summary and Conclusions


Table 10 gives a summary of the results of the machining tests.

Some of the species tested are consistently better than average in most
respects and some are consistently poorer. Some are good in one property and
poor in others. These things are equally true of native hardwoods. In general
the tropical woods machined about as well as do our native hardwoods and with
most of them at least it seems unlikely that machining difficulties would
restrict their use much. The woods tested had a specific gravity range about
equal to that between basswood and hickory. Within this range, which includes
the great bulk of tropical hardwoods, the machining tests that were used
appear to be equally applicable to native and tropical hardwoods.


Report No. R1744


-5-




Table l.--Planing
SP-laning :
;properties : Planing defects
Species : ----------- : --------------------------------
;Defect-free: Raised : Fuzzy : Chipped
; pieces ; grain : grain : grain
- ----------------------------- ----------- -------- ---------;--------


Anacardium sp,
Brosimum alicastrum group
Calophyllum brasiliense
Carapa guianensis
Cordia alliodora group
Dialyanthera sp.
Enterolobium cyclocarpum
Hieronyma alchorneoides
Nectandra sp.
Nothofagus spf
Prioria copaifera
Symphonia globulifera
Virola sp.
Vochysia hondurensis
Zanthoxylum sp.


Percent

15
70
43
33
75
50
35
20
75
90
85
50
60
33
75


:Very common:Very common:


SNone
SCommon :
STrace
STrace
STrace
Common
Common
SCommon
SNone
None
SCommon
Trace
;Very common:
: None


None
Trace
Trace
None
Trace
Trace
None
None
None
None
None
Trace
None
None


None
Common
Common
C onmmon
None
Trace
Common
Common
Trace
None
Trace
Common
Trace
Trace
Trace


Table 2.--Shaping
: Shaping
:properties; Shaping defects
Species ---------- -------------------------- -
: Good to ; Rough : Raised :Chipped
excellent ; end grain : grain grain
: pieces
------------------------------------------------------- ---------- r-:--------
SPercent

Anacardium sp. 50 ;Very common: Common : Trace
Bro-irr.um .licastrum group 60 :Very common: None i Trace
Calophyllum brasiliense 45 :Very common; Common : Trace
Carapa guianensis 28 :Very common;Very common: Trace
Cordia alliodora group : 50 ;Very common; Common : None
Dialyanthera sp. 40 :Very common;Very common: None
Enterolobium cyclocarpum 45 :Very commons None : Trace
Hieronyma alchorncoides : 40 :Very common: None : Trace
Nectandra sp. : 50 :Very common: Common : None
Nothofagus sp, : 67 : Trace : Tone :Tone
Prioria copaifera : 50 :Very common; Trace : hone
Symphonia globulifera : 40 ;Very common: Common : None
Virola sp, 45 ;Very common;Very common: None
Vochysia hondurensis 43 :Very common: Common : Trace
Zanthoxylumn sp. : 50 :Very common; None : None


Report No, R1744




Table 3.--Turning


: Turning
: properties


Turning defects


. -------------- ------------- ---------------


SGood to
Excellent
: pieces


: Surface : Poor : Tearouts
: roughness : detail :


-------- -------------------------------.-----------*-------------------


Anacardium sp.
Brosimrum alicastrum group
Calophyllum brasiliense
Carapa guianensis
Cordia alliodora group
Dialyanthera sp.
Enterolobium cyclocarpum
Hieronyma alchorneoides
Nectandra sp.
Prioria copaifera
Symphonia globulifera
Virola sp.
Vochysia hondurensis
Zanthoxylum sp.


Percent

70
90
70
70
83
50
75
80
80
80
83
50
40
90


Common
Trace
Common
Common
Common
Trace
Common
Trace
Common
Trace
Common
Trace
Common
Trace


x


x






x
x
X :






X :
X :


None
None
None
None
None
Few
None
:None
None
'Tone
None
Few
Few
None


Table 4.--Sanding
Scratch-free pieces : Fuzz-free pieces
Species -------------------- :------------------
: 1/o grit : 3/0 grit :1/0 grit:3/0 grit
-----------------------------------------------------------------------------


Anacardium sp.
Brosimumn alicastrum group
Calophyllum brasiliense
Carapa guianensis
Cordia ailiodora group
Dialyanthera sp.
Enterolobium cyclocarpum
Hieronyma alchorneoides
Nectandra sp.
Nothofagus sp.
Prioria copaifera
Symphonia globulifera
Virola sp.
Vochysia hondurensis
Zanthoxylum sp.


: Percent

100
S 33
S 88
100
100
50
S 85
S 90
100
S 0
100
100
S 70
S 90
100


SPercent

100
S 100
100
100
* 100
100
100
100
100
100
100
100
100
100
100


Report No. R1744


Species


:Percent

0
: 67
0
16
0
0
36
100
33
20
0
16
0
30
33


Percent

0
100
88
50
100
80
73
100
67
100
50
83
80
70
100




Table 5,--Boring
S Good to : Amount of
Species : excellent holes- : offsize
-------------------------------------------------------.-..--
Percent : Inch


Anacardium sp.
Brosimum alicastrum group
Calophyllum brasiliense
Carapa guianensis
Cordia alliodora group
Dialyanthera sp.
Enterolobium cyclocarpum
Hieronyma alchorneoides
Nectandra sp.
Nothofagus sp.
Prioria copaifera
Symphonia globulifera
Virola sp.
Vochysia hondurensis
Zanthoxylum sp.


90
77
86
100
50
95
100
75
84
75
100
50
62
83


0.0012
.0002
.0006
.0011
.0015
.0008
.0003
.0020
.0013
.0024
.0009
.0008
.0015
.0010
.0010


-Based on smoothness of cut.


Table 6.--Mortising


Species


: Fair to 1
: excellent holes-


-----------------------------


Percent

90
100
78
72
75


Anacardium sp.
Brosimum alicastrum group
Calophyllum brasiliense
Carapa guianensis
Cordia alliodora group
Dialyanthera sp.
Enterolobium cyclocarpum
Hieronyma alchorneoides,
Nectandra sp.
Nothofagus sp.
Prioria copaifera
Symphonia globulifera
Virola sp,
Vochysia hondurensis
Zanthoxylum sp.


80
100
67
100
55
100
30


SAmount of
offsize

Inch

0.0038
S .0028
.0027
: .0028
S .0032
S .0077
S .0030
S .0028
S .0049
S .0041
.0034
.0030
S .0052
: .0043
: .0034


-Based on smoothness of cut*


Report No. R1744




Table 7.--Specific gravity
(Based on oven-dry weight and green volume)


Sn- cies


: .lean -: inirrlr. : -aximum


Anacardium sp.
Srosimumi alicastrum group
Calophyllum brasiliense
Carapa gi.iianensis
Cordia alliodora group
Dialyanthera sp.
Enterolobium cyclocarpum
Hieronyma alchorneoides
Nectandra sp.
Nothofagus sp.
Prioria copaifera
Symphonia globulifera
Virola sp.
Vochysia hondurensis
Zanthoxylum sp.


0.463
.620
.490
.496
.489
.351
: .456
.651
.422
.542
.416
.544
.410
: .415
.588


0.403
.575
.444
.427
.460
.313
.392
.580
.395
.4c98
.376
.470
.380
.383
.505


S 0.540
S .680
.530
S .580
S .510
.416
S .546
.700
S .465
S .595
.477
.593
.465
.456
* .683


Table 8.--Cross grain


Spiral grain
Percent of
s1ope--


SInterlocked grain
* Percent of
: pieces


-----------------------------------------------------------------


Anacardium sp.
Brosimum alicastrum group
Calophyllum brasiliense
Carapa guianensis
Cordia alliodora group
Dialyanthera s? .
Enterolobium cyclocarpum
Hieronyma alchorneoides
Nectandra sp.
Nothofagus sp.
Prioria copaifera
Symphonia globulifera


Vochysia hondurensis
Zanthoxylum sp.


C.3
6.5
7.7
3.1
6.7


100
25
50
50
0
5
100
100
67


: 4.0
: 2.5
* 3.4
: 5.5


: 6.2 : 50
S 4.4 : 0


-Applies only to pieces that are free


from interlocked grain.


Report No. R1744


Specie s


---------------------------.----- :- -- - - ------------ :-----------





Table 9.--Shrinkage (from green to oven-dry)
All : Radial : Tangential
Species : samples : only : only
------------------------- ----------------- --------- ------------
Percent : Percent : Percent


Anacardiumn sp.
Brosimum alicastrum group
Calophyllum bras ilense
Carapa guianensis
Cordia alliodora group
Dialyanthera sp.
Enterolobium cyclocarpum
Hieron'na alchorneoides
Nectandra sp.
ITothofagus sp.
Prioria copaifera
Symphonia globulifera
Vochysia hondurensis
Zanthoxylum sp.


4.6
6.9
8.7
7.6
6.5
8.6
4.5
5.6
5.2
8.6
5.2
7.4
3.6
6.7


4.1 : 5.8
:.........; 6.9
:.........; 8.7
6.4 : 9.3
......... 6.5
......... 8.6
: 3.0 : 5.4
: 4.8 : 6.4
: 4.1 : 6.2
:0......... 8.6
4.4 : 5.6
:0....... .: 7.4
: 2,8. : 6.5
:.... .....: 6.7


Ca1~
C
-& ~ z
0 ~ m
AJ~ ~
~ 0)
0 ~ -<
AZZ~
I-


Table 10.--Summary


of machining properties


:Planing: Shaping : Turning : Sanding : Boring :Mortising
:defect-; good to : good to :fuzz-free: good to : fair to
Species : free :excellent:excellent: pieces .excellent:excellent
: pieces: pieces : pieces : : pieces : pieces
--------.. ------- --: .------- ------- ----;-------


:Percent: Percent


Anacardium sp. : 15
Broslinum alicastrum group: 70 :
Calophylilum brasiliense : 43 :
Carapa guianensis : 33
Cordia alliodora group : 75 :
Di]::anthera sp. : 50
Ent--,lobium cyclocarpum : 35
Hier i/yma alchorneoides : 20
citandra sp. : 75
Yothofagus sp. : 100
Prioria copaifera : 85
oymphonia globulifera : 50
Vir-jla sp. 60 :
VochiYcia hondurensis : 33
Z'" I x' lun sp. : 75

Mean of 1i tropical
hardwoods : 53
% in of 25 native hard- :
woods 61


47 :

25 :


: Percent :

70
90
70
70 :
83
50
75 :
80 S
80

80
83
50 :
40
90


73 :
79
79


Percent : Percent

0 : 70.
100 : 90
88 : 78
50 : 86
100 : 100
80 50
73 : 95
100 : 100
67 : 75
100 : 84
50 : 75
83 : 100
80 50
70 : 62
100 : 83


76 : 81

62 : 89


Percent

90
100
78
72
75
11
80
100
67
100
55
100
30
75
50


72

70


Report .'-.. R1744