GB/T 42608-2023 Portable chain-saws - Kickback test
1 Scope
This document specifies the methodology for determining the kickback potential of gasoline-powered and electric-powered (including battery powered) chain-saws, complete with guide bar and saw-chain (hereafter referred to as chain).
This document has been demonstrated to be an accurate method of measurement for evaluating computed kickback angles and energy associated with chain-saw kickback for electric-powered chain- saws (including battery powered) and gasoline-powered chain-saws with engine capacity up to 80 cm³. It is not intended to evaluate chain-saws with an engine capacity of above 80 cm³. Furthermore, because of physical size limitations of the kickback machine, it is not intended for testing of units with guide bar cutting length in excess of 63 cm.
Modifications to the methodology for determining the kickback potential introduced in this document are aimed to have a better reproducibility of the results; test results obtained according to the previous methodology still maintain their validity.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 6531 Machinery for forestry - Portable chain-saws - Vocabulary
Note: GB/T 18960-2023 Potable china-saws - Vocabulary (ISO 6531 : 2017, IDT)
ISO 6535 Portable chain-saws - Chain brake performance
Note: LY/T 2890-2017 Portable chain-saws - Chain brake performance (ISO 6535 : 2015, IDT)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 6531 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
- ISO Online browsing platform: available at https://www.iso.org/obp;
- IEC Electropedia: available at http://www.electropedia.org/.
3.1
bar nose radius
continuous radius formed on the top portion of the bar from the centreline of the bar to an angle 35° above the centreline
Note: See Figure 1.
3.2
manually activated chain brake
chain brake which is intended to be actuated by the hand of the operator
3.3
contact angle
angle between the surface of the test specimen and a perpendicular to the guide bar centre line
3.4
data set
group of data points, all taken at the same test conditions
3.5
horizontal system
portion of the kickback machine used to measure the horizontal (linear) energy of the kickback reaction
3.6
impact
test sequence involving releasing the test specimen at a specified speed into contact with the moving saw-chain at the guide bar tip to create a simulated kickback reaction
3.7
rotary system
portion of the kickback machine used to measure the rotary energy of the kickback reaction
3.8
specimen
test specimen
block of medium density fibreboard used as an object for the saw-chain to engage in a simulated kickback
4 Test method
4.1 Principles
The flat surface of the test specimen (MDF) is thrust into contact with the moving saw-chain at the tip of a chain-saw guide bar at a specified speed in order to produce a simulated kickback reaction. This takes place under controlled conditions in the kickback machine, which is designed to measure the magnitude of rotary and horizontal energies generated during the resulting kickback reaction.
A step-by-step search, covering a range of critical test conditions, determines the peak energy values to be used in calculating the computed kickback angle(s) CKA using the analytical model. This peak value is intended to simulate the most severe conditions reasonably expected to be encountered by typical users.
Since there may be some variability, several impacts are made under each set of conditions and the results averaged.
Note: Test parameters such as approach speed, engine speed, shape and type of test materials have been established to permit consistent evaluation of a wide range of cutting attachment and type of power heads and to simulate kickback situations found in actual practice.
4.2 Chain-saw configuration
4.2.1 General
The worst-case configuration (e.g., saw-chain with the highest kickback magnitude) can be demonstrated on a chain-saw with cutting attachments of the same class and pitch.
4.2.2 Chain-saw families
For the purposes of chain-saw qualification, saws that have an engine displacement within 20% and similar mass distribution (having centre of gravity coordinates within ±5 mm, a mass tolerance of ±0.2 kg, and a polar moment of inertia [PMI] tolerance of ±10%) shall be regarded as being equivalent to one another. However, if a saw family within this range is to be qualified, at least the largest displacement saw shall be tested.
4.2.3 Requirements for testing bars and saw-chains
A guide bar with the largest bar nose radius and/or the greatest number of sprocket teeth represents the highest energy configuration and covers all other bars of the same length with a smaller radius. Tests need not be repeated for saw-chains that have been documented to have lower kickback potential than the highest kickback energy saw-chain on equivalent types of chain-saws.
At a minimum, testing shall be performed with the largest bar nose radius of the manufacturer's designated standard guide bars recommended for sale to the end-user. If multiple bar lengths are listed in the operator's manual, the longest, shortest, and one other length shall be tested. If the kickback test results for each of these lengths are less than 35° CKA, all other lengths shall be accepted. If any guide bar exceeds 35° CKA, all bar lengths shall be tested.
4.3 Equipment and materials to determine CKA
4.3.1 Computer program, as specified in Annex A, to compute the kickback angle using measured inputs.
4.3.2 Chain-saw kickback test machine for energy level measurements.
4.3.3 Engine speed indicator with an accuracy of ±1.5% of the measured value.
4.3.4 Carriage-velocity timing device, including probes with an accuracy of ±1 ms.
4.3.5 Timer control switch box.
4.3.6 Test specimens, consisting of medium-density fibreboard (MDF) samples, 38 mm×38 mm×250 mm or 38 mm×76 mm×250 mm. The samples shall be oriented with the rough side (end grain) facing the bar tip. The density range shall be 737 kg/m3 ± 32 kg/m3.The samples shall have a hardness of 2892 N ± 667 N, the method for determining fibreboard hardness is specified in Annex B.
4.3.7 Chain-brake actuating apparatus (for complete chain-saw tests only).
Note: The bill of materials and engineering drawings describing a kickback test machine, the kickback calculation program, and a manual entitled “Chain-saw Kickback Test Machine -Principles of Operation” are available on request from the Outdoor Power Equipment Institute, 341S Patrick St, Alexandria, VA 22314, USA
4.4 Preparation
4.4.1 General
Record all measurements on the kickback test record (see Figures C.1 and C.2).
4.4.2 Physical measurements of chain-saw
4.4.2.1 Prior to taking measurements prepare the chain-saw and saw-chain in accordance with 4.4.4. The physical measurements listed in 4.4.2.2 to 4.4.2.4 shall be made with the guide bar and saw-chain attached in proper working position and with oil and fuel tanks full.
4.4.2.2 Measure the chain-saw mass in kilograms. An accuracy of ±50 g is acceptable for this measurement.
4.4.2.3 Determine the location of axis of rotation, through the centre of gravity, perpendicular to the plane of the guide bar. It is to be marked on the saw body. An accuracy of ±6 mm is acceptable for this measurement.
4.4.2.4 Determine the chain-saw polar moment of inertia (PMI) about an axis through the centre of gravity and perpendicular to the plane of the guide bar, in kilograms metre squared. A procedure for determining the polar moment of inertia is presented in Annex D.
Standard
GB/T 42608-2023 Portable chain-saws—Kickback test (English Version)
GB/T 42608-2023 Portable chain-saws - Kickback test
1 Scope
This document specifies the methodology for determining the kickback potential of gasoline-powered and electric-powered (including battery powered) chain-saws, complete with guide bar and saw-chain (hereafter referred to as chain).
This document has been demonstrated to be an accurate method of measurement for evaluating computed kickback angles and energy associated with chain-saw kickback for electric-powered chain- saws (including battery powered) and gasoline-powered chain-saws with engine capacity up to 80 cm³. It is not intended to evaluate chain-saws with an engine capacity of above 80 cm³. Furthermore, because of physical size limitations of the kickback machine, it is not intended for testing of units with guide bar cutting length in excess of 63 cm.
Modifications to the methodology for determining the kickback potential introduced in this document are aimed to have a better reproducibility of the results; test results obtained according to the previous methodology still maintain their validity.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 6531 Machinery for forestry - Portable chain-saws - Vocabulary
Note: GB/T 18960-2023 Potable china-saws - Vocabulary (ISO 6531 : 2017, IDT)
ISO 6535 Portable chain-saws - Chain brake performance
Note: LY/T 2890-2017 Portable chain-saws - Chain brake performance (ISO 6535 : 2015, IDT)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 6531 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
- ISO Online browsing platform: available at https://www.iso.org/obp;
- IEC Electropedia: available at http://www.electropedia.org/.
3.1
bar nose radius
continuous radius formed on the top portion of the bar from the centreline of the bar to an angle 35° above the centreline
Note: See Figure 1.
3.2
manually activated chain brake
chain brake which is intended to be actuated by the hand of the operator
3.3
contact angle
angle between the surface of the test specimen and a perpendicular to the guide bar centre line
3.4
data set
group of data points, all taken at the same test conditions
3.5
horizontal system
portion of the kickback machine used to measure the horizontal (linear) energy of the kickback reaction
3.6
impact
test sequence involving releasing the test specimen at a specified speed into contact with the moving saw-chain at the guide bar tip to create a simulated kickback reaction
3.7
rotary system
portion of the kickback machine used to measure the rotary energy of the kickback reaction
3.8
specimen
test specimen
block of medium density fibreboard used as an object for the saw-chain to engage in a simulated kickback
4 Test method
4.1 Principles
The flat surface of the test specimen (MDF) is thrust into contact with the moving saw-chain at the tip of a chain-saw guide bar at a specified speed in order to produce a simulated kickback reaction. This takes place under controlled conditions in the kickback machine, which is designed to measure the magnitude of rotary and horizontal energies generated during the resulting kickback reaction.
A step-by-step search, covering a range of critical test conditions, determines the peak energy values to be used in calculating the computed kickback angle(s) CKA using the analytical model. This peak value is intended to simulate the most severe conditions reasonably expected to be encountered by typical users.
Since there may be some variability, several impacts are made under each set of conditions and the results averaged.
Note: Test parameters such as approach speed, engine speed, shape and type of test materials have been established to permit consistent evaluation of a wide range of cutting attachment and type of power heads and to simulate kickback situations found in actual practice.
4.2 Chain-saw configuration
4.2.1 General
The worst-case configuration (e.g., saw-chain with the highest kickback magnitude) can be demonstrated on a chain-saw with cutting attachments of the same class and pitch.
4.2.2 Chain-saw families
For the purposes of chain-saw qualification, saws that have an engine displacement within 20% and similar mass distribution (having centre of gravity coordinates within ±5 mm, a mass tolerance of ±0.2 kg, and a polar moment of inertia [PMI] tolerance of ±10%) shall be regarded as being equivalent to one another. However, if a saw family within this range is to be qualified, at least the largest displacement saw shall be tested.
4.2.3 Requirements for testing bars and saw-chains
A guide bar with the largest bar nose radius and/or the greatest number of sprocket teeth represents the highest energy configuration and covers all other bars of the same length with a smaller radius. Tests need not be repeated for saw-chains that have been documented to have lower kickback potential than the highest kickback energy saw-chain on equivalent types of chain-saws.
At a minimum, testing shall be performed with the largest bar nose radius of the manufacturer's designated standard guide bars recommended for sale to the end-user. If multiple bar lengths are listed in the operator's manual, the longest, shortest, and one other length shall be tested. If the kickback test results for each of these lengths are less than 35° CKA, all other lengths shall be accepted. If any guide bar exceeds 35° CKA, all bar lengths shall be tested.
4.3 Equipment and materials to determine CKA
4.3.1 Computer program, as specified in Annex A, to compute the kickback angle using measured inputs.
4.3.2 Chain-saw kickback test machine for energy level measurements.
4.3.3 Engine speed indicator with an accuracy of ±1.5% of the measured value.
4.3.4 Carriage-velocity timing device, including probes with an accuracy of ±1 ms.
4.3.5 Timer control switch box.
4.3.6 Test specimens, consisting of medium-density fibreboard (MDF) samples, 38 mm×38 mm×250 mm or 38 mm×76 mm×250 mm. The samples shall be oriented with the rough side (end grain) facing the bar tip. The density range shall be 737 kg/m3 ± 32 kg/m3.The samples shall have a hardness of 2892 N ± 667 N, the method for determining fibreboard hardness is specified in Annex B.
4.3.7 Chain-brake actuating apparatus (for complete chain-saw tests only).
Note: The bill of materials and engineering drawings describing a kickback test machine, the kickback calculation program, and a manual entitled “Chain-saw Kickback Test Machine -Principles of Operation” are available on request from the Outdoor Power Equipment Institute, 341S Patrick St, Alexandria, VA 22314, USA
4.4 Preparation
4.4.1 General
Record all measurements on the kickback test record (see Figures C.1 and C.2).
4.4.2 Physical measurements of chain-saw
4.4.2.1 Prior to taking measurements prepare the chain-saw and saw-chain in accordance with 4.4.4. The physical measurements listed in 4.4.2.2 to 4.4.2.4 shall be made with the guide bar and saw-chain attached in proper working position and with oil and fuel tanks full.
4.4.2.2 Measure the chain-saw mass in kilograms. An accuracy of ±50 g is acceptable for this measurement.
4.4.2.3 Determine the location of axis of rotation, through the centre of gravity, perpendicular to the plane of the guide bar. It is to be marked on the saw body. An accuracy of ±6 mm is acceptable for this measurement.
4.4.2.4 Determine the chain-saw polar moment of inertia (PMI) about an axis through the centre of gravity and perpendicular to the plane of the guide bar, in kilograms metre squared. A procedure for determining the polar moment of inertia is presented in Annex D.
