Evaluation of working quality of timber under different woodworking operations- Method of test
1992 Edition

Overview

• Defines preparation techniques and dimensions for test specimens used in various woodworking assessments.

Specimen Dimensions

Machine Details

• No rigid machine specifications mandated.
• Essential to document machine type, operating parameters (feed rate, cutter head speed, power), and tooling used.

Data Logging

• Use standardized forms to record wood species, moisture level, feed speed (mm/s), rotation speed (rev/min), number of knives, cutting angle, and surface defects such as raised or fuzzy grain, chip marks, crushing, and tearout.

This section ensures uniform specimen preparation and consistent recording for comparative machining performance evaluation.

Important Terms

• Timber technology terms are clarified, with references to IS 707:1976 for extended definitions.
• Moisture content's critical role in machining quality is emphasized.

Cutting Parameters Recorded

• Species
• Moisture content percentage
• Feed rate in mm/s
• Rotational speed in revolutions per minute
• Number of cutting knives
• Tool cutting angle in degrees

Surface Defect Categories

• Defect-free
• Raised grain roughness
• Fuzzy grain
• Torn grain (tearout)
• Chip marks
• Crushing
• Charges

Data Recording Table Example

This terminology framework enhances clarity and precision in timber machining assessments.

Specimen Sizes for Defect Evaluation

Defect Recording

• Surface imperfections recorded include raised grain roughness, fuzzy grain, torn grain, chip marks, crushing, and charges.

Testing Notes

• Moisture content and specific gravity measured according to IS 1708.
• Holes are machined both along and across the grain to examine roughness, tearout, fuzziness, crushing, and charring.
• Feed rate, rotational speed, number of knives, and cutting angle are documented to correlate with defect occurrence.

This section provides a structured inspection framework to ensure consistent identification of machining defects.

Specimen Sizes and Quantity

Preparation Details

• Specimens must be prepared by planing and sanding to achieve uniform thickness and surface smoothness.
• Samples should represent the batch uniformly and be free from natural defects.
• Preparation must follow the diagrams and instructions specified (e.g., Fig. 1 in the standard).

Standardized specimen preparation ensures reproducibility and reliability of test outcomes.

Machine Specifications

• No fixed specifications mandated due to equipment market diversity.
• Important to record machine details: feed speed, cutter head speed, horsepower, and tooling.

Testing Instrumentation

• Depth of cut measured using dial gauges.
• Power consumption monitored via wattmeters.

Turning Lathe Specifications

• Commercial woodworking lathe operating approximately at 3000 rpm.
• Turning tools shaped as per the provided diagrams or standard tool configurations.

This section stresses the importance of detailed machine parameter documentation to maintain test consistency.

Specimen Sizes for Various Tests

Test Setup

• Use dial gauges for precise depth measurement.
• Connect wattmeters to capture power usage during machining.

Tool Maintenance

• Cutting blades and bits must be regularly sharpened and comply with Indian standards.

Data Recording

• Record parameters such as wood species, moisture content, feed rate, rotational speed, number of knives, and cutting angle.
• Log surface defects including raised grain roughness, fuzzy grain, torn grain, chip marks, crushing, and tearout.

Employing these procedures ensures accurate and comprehensive data for timber workability evaluation.

Moisture Content Determination

• Performed using the oven-dry method as described in IS 1708 Part 1.
• Calculated by the formula:

[ Moisture\ Content\ (%) = \frac{W_{wet} - W_{dry}}{W_{dry}} \times 100 ]

where (W_{wet}) is the weight before drying, and (W_{dry}) is the weight after drying at 103 ± 2°C until constant weight.

Specific Gravity Measurement

• Conducted using the water displacement method according to IS 1708 Part 2.
• Calculated as:

[ Specific\ Gravity = \frac{Oven\ dry\ weight\ in\ air}{Oven\ dry\ weight\ in\ air - Weight\ in\ water} ]

Conditioning

• Samples conditioned to 12 ± 2% moisture content.
• Environmental conditions maintained at 65 ± 5% relative humidity and 27 ± 2°C temperature.

Accurate determination of these parameters is vital for meaningful machining quality assessment.

Grading of Specimens

• Individual defects are scored from 1 to 5 depending on severity.
• Total defect score is the sum of all defect ratings per specimen.

Rating Factor (RF) Computation

[ RF = \frac{Number\ of\ specimens\ in\ specified\ grades}{Total\ specimens} \times 100% ]

Data Recording

• Record species, moisture content, feed rate, speed, number of knives, and cutting angle.
• Document specific defects and assign scores accordingly.

This grading and evaluation method facilitates quantitative analysis of timber machining quality.

Data Logging Guidelines

• After each woodworking test, conduct a visual inspection to identify defects.
• Assign numerical defect scores from 1 (minor) to 5 (severe) for each defect type.
• Calculate the total defect score by summing individual defect values per specimen.

Data Collection Table

Defect Categories

Specimen Dimensions Reference

Consistent data recording is critical for reliable assessment and comparison.

Rating Factor (RF) Calculation

Working Quality Index Formula

• Adjusting Factor (AF): Normalizes results relative to teak’s planing test.

• Weighted Average (WA):

[ WA = \frac{\sum (RF \times AF \times W)}{EW} ]

Where:

• Composite Rating Factor (CRF):

[ CRF = \frac{WA_{species}}{WA_{teak}} \times 100 ]

• Ease Factor (EF):

[ EF = \frac{Power_{teak}}{Power_{species}} \times 100 ]

• Working Quality Index (WQI):

[ WQI = CRF + 2 \times (EF)^3 ]

Interpretation

• The WQI integrates both performance grading and ease of machining relative to teak.
• Higher WQI values indicate superior working quality.

This quantitative index assists in comparing timber species for suitability in woodworking applications.