The E-grader was developed as a joint project
between Falcon Engineering Limited and Forest
Research. The E-grader won the 2001 IPENZ award
for Manufacturing Engineering Excellence.
The E-grader individually stress
tests timber products so they can then be certified for use as
a structural member. This Mechanical Grading of timber
is more accurate than traditional visual grading and gives, directly,
an MoE value and a resulting MGP (Machine Graded Pine) rating to the timber product.
For instance:
MGP 8 is a direct substitute for visually graded No.1 framing.
Scientists at New Zealand Forest Research have evaluated the requirements
of the standard and have then compared that with the strength
properties of MGP 8. They published in their Sawmilling
Bulletin, the following conclusion:
“MGP8 may be safely sold
as a direct substitute for Radiata Pine visually graded No.1 framing
grade”
From Issue No.28 December 2000.
Please
click MGP- What is it, above to find out more on Machine Graded Pine.
The E-grader's development has been based around three
objectives:
1. To utilise the fact that long span on edge stiffness
testing (LmoEj) is a better predictor of strength and stiffness
than the traditional stress grader parameter of MoEpmin..
2. The need to provide a lower cost stiffness grader with
simpler, more understandable testing compared to traditional
machine stress graders whilst maintaining similar volume throughput.
3. To handle virtually all timber sizes, in all conditions
-roughsawn or gauged, green or dry. The basic operation
of the E-grader™ is to perform one stiffness test (LMoEj)
per piece. Essentially the operator inputs the timber dimensions,
the load spans, and the loads at which the timber deflections
are to be recorded. Using this information the Egrader™
calculates the actual stiffness for the piece. This approach
is quite different to traditional stiffness graders, which determine
the stiffness at many intervals along the piece. The single
stiffness measurement approach closely resembles the way lumber
is used in practice.
To date the E-grader™ has the following
features:
Ability to grade up to 20+ pieces per minute (200+m3
per hour shift on 100x50 . Model 200)
Determines long span stiffness as a joist (and if
required long span stiffness as a plank . Model 100)
Caters for all timber sizes from 75x45 to 300x100
and 100x100. Note: Traditional stress graders can
only grade up to 75mm maximum thickness and then in gauged
, K/D form).
Has a variable span capability.
Has the ability when linked to a computer to record
the grading stiffness for data capture and log resource evaluation
purposes.
Can be linked to either grade spray guns or an inkjet
marker for on-line timber marking.
The E-grader™ will be able to stiffness grade
and then potentially apply a proof load in one operation if
required.
Some of the information above has been taken from:
Sawmilling
Issue No. 27 May 2000
THE FOREST RESEARCH E-GRADER™
MORE VALUE FROM IMPROVED STRUCTURAL LUMBER GRADING
By: Doug Gaunt, Mike Collins and John Roper
<--Back to Top-->
