Evaluation of Non-Wheat Noodle Machine Design with An Ergonomic Approach

. Designing machines without involving the human factor can cause users discomfort, fatigue, and health problems. Ergonomic criteria when designing machines can increase user effectiveness. PT. Noang Prima Utama uses an extruder to produce pasta under the “LocaPasta” brand. Complaints of pain in the neck and back for 1-3 days due to standing position, bending down, and arms reaching forward for a long-time during production. The research objective was to evaluate the extruder design using the anthropometric method. Anthropometric data were tested for uniformity, data adequacy, and the determination of percentiles. Machine dimensions were compared with user anthropometer data for design improvement. When feeding materials into the hopper, the operator’s working posture needed to be more ergonomically adequate due to raised arms and pushing the material bit by bit (repetitively). The evaluation of the machine design based on anthropometric dimensions reveals several improvements. The redesigned extruder machine includes changes such as adjusting the footstep height to 27.7 cm so that the height of the setting box to 120.95 cm from the footstep (adjusting to standing shoulder height), allowing rotation of the setting box and the hopper height from the footstep is parallel to the standing elbow height which is 92.1 cm. With the implementation of the new prototype, the operator’s working posture no longer involves bending over while adjusting the machine, and the arms can comfortably rest on the hopper while feeding the material.


Introduction
Designing machines that consider ergonomic factors is crucial for ensuring user comfort, health, and productivity.Neglecting the human factor lead to discomfort, fatigue, and even injury.Workers in the food processing industry often have to stand in a fixed position for long hours, leading to musculoskeletal disorders.Hence, incorporating ergonomic principles in machine design is essential to promote workers' well-being and enhance production efficiency.The ergonomic design has been proven effective in enhancing workers' comfort and productivity in various industries, including food processing.Workers in the food processing industry are often exposed to repetitive motions, awkward postures, and heavy lifting, leading to musculoskeletal disorders.Therefore, incorporating ergonomic principles in machine design can significantly reduce these issues and promote workers' well-being.
Several studies have been conducted to evaluate the ergonomic design of machines in the food processing industry, one regarding the anthropometric study.The anthropometric approach in machine design is highly recommended for comfortable use by operators [1], in which this approach measures body dimensions [2].For example, a study by Shukla et al. (2022) regarding the design of dimensions of a self-propelled combine harvester chair based on anthropometric data with the aim of improving posture comfort [3].
Some studies highlight the importance of ergonomics in designing equipment to ensure the safety and health of users.Among them, Laal et al. (2017) evaluated the working position of drivers who are at risk of experiencing MSDs and analyzed data on handling discomfort while driving felt in the lower back, upper back, knees, shoulders, arms, hips, ankles, and elbows.The study stated that anthropometric databases that can be used in designing ergonomic chairs help reduce the risk of MSDs [4].Wedantara et al. (2018) modified the pandan leaf chopper ergonomically.Currently, complaints that are felt by users (operators) include pain in the back, waist, and arms.Researchers utilize anthropometric data to modify the tool by changing the dimensions of the tool.The results of the evaluation score show that every point of the Nordic Body Map is in the category of not sick, and the work productivity of the machine had increased compared to the engine before it was modified [5].Hamdy and Syamzalisman (2018) conducted an ergonomic analysis using work postures and designing cracker drying facilities, bending and squatting movements when working for long periods cause fatigue and injury.Based on an assessment using the Rapid Entire Body Assessment (REBA), work posture loads include a high risk of injury to the muscles.The anthropometric data obtained is used to design work tools.The evaluation results showed an improvement in work posture from a high level to a low one which means it does not cause muscle injury [6].Mayasti et al. (2023) evaluated the design of a drying machine based on anthropometry.The results showed that the work posture is less ergonomic.They suggested making a stair to prevent users from tiptoeing and modifying the panel box height to avoid a squat position [7].
Ergonomic evaluation can also be conducted by analyzing complaints regarding musculoskeletal disorders (MSDs) experienced by workers.One method to analyze muscle complaints is using the Nordic Body Map (NBM), an ergonomic checklist questionnaire accompanied by a body map to identify the location of musculoskeletal complaints in workers [8].
Musculoskeletal disorders (MSDs) affect soft tissues such as muscles, joints, ligaments, tendons, cartilage, and the nervous system.Body parts commonly affected by MSDs include the hands, wrists, fingers, neck, spine, legs, and shoulders.However, the most frequent occurrences are in the arms and spine [9].Several conditions that may lead to MSD symptoms include excessive force exertion, repetitive movements, awkward posture, unsupported positions, static positions requiring prolonged endurance, and movements involving increased speed during bending or twisting.
Nilamsari and Innafin (2022) identified the risks of developing MSDs based on subjective complaints (NBM) reported by workers and work posture analysis [10].The subjective complaints (NBM) indicated that two respondents experienced high-risk complaints.In contrast, one respondent reported a moderate-risk level of complaints, with a significantly high average level of pain in the left shoulder, right shoulder, upper right arm, and lower back.The work posture analysis fell into the very high-risk category.
Several studies have been conducted to optimize the pasta-making process with ergonomic principles in the context of pasta production.For example, the study of Buczaj et al. (2012) evaluated the physical and psychological loads and material factors of the work environment in the pasta industry.The results of the analysis show that physical stress in the workplace results in the danger of musculoskeletal disorders and exposure to allergens, thus requiring further studies to reduce the physical burden in the pasta industry [11].
Ashri et al. ( 2022) also reported problems with producing noodles or pasta-the analysis of MSD risk in the noodle production line at PT. Noang Prima Utama-Subang revealed that the working posture of operators while operating the noodle extruder or molder had a high level of ergonomic risk [12].Operators experienced pain complaints during production, mainly when feeding the dough into the extruder hopper until all the ingredients were molded into noodle strands.Based on the Nordic Body Map questionnaire, operators reported experiencing three days of stiffness in their back and neck.
Considering the challenges in non-wheat noodle production, this study aims to address the issues related to the extruder machine.The research evaluates the machine based on an anthropometric approach.It assesses the ergonomics of a machine by analyzing the working posture during extruder operation, identifying operator complaints using the Nordic Body Map, and analyzing design improvements using an anthropometric approach.Based on the evaluation results, improvements were made to develop a new prototype design.

Method
The design in this study includes (1) [13].

Determining the number of respondents/tool operators
Respondents for measuring anthropometric dimensions were 14 extruder operators/users, while the tool to be evaluated was the extruder tool.Data collection is located at the machine testing laboratory -PRTTG in March -May 2023.This research used stationary data recorders, machine dimension measuring tapes, anthropometer sets, cameras for work posture, and SPSS for data analysis.

Anthropometric measurements
Measurement of the operator's body dimension data (anthropometry) adjusts to the current working posture operating the extruder.The anthropometric data will be used to evaluate the suitability of the machine's dimensions with the operator.The dimensional data from anthropometry related to the extruder is presented in Table .1The horizontal distance from the top of the left shoulder to the tip of the middle finger of the left hand, with the left elbow and wrist straight.

D25a
The horizontal distance from the top of the right shoulder to the center of the cylinder held by the right hand, with the right elbow and wrist straight.

D25b
The vertical distance from the floor to the top of the head.

D26a
The vertical distance from the floor to the outer corner of the right eye.

D26b
The vertical distance from the floor to the outer corner of the left eye.

Testing of uniformity and adequacy of data
Tests for adequacy and uniformity of data are needed to find out whether the amount of data taken is adequate and uniform.If the data is adequate and uniform, the data is declared valid.The formula for calculating the amount of data needed can be seen in Equation 1and for calculating the uniformity of data can be seen in Equation ( 2) and (3).

Adequancy calculation
The data adequacy test formula is presented in Equation 1. (1) ∑.Note = N' = the amount of data needed; N = the amount of data, K = confidence level of the index coefficien; S = accuracy level; x = variable value, if N'<N then the data is adequate

Uniformity calculation
The data is uniform if it is within the upper and lower limits.Upper Control Limit (UCL) = x̅ + k σ; Lower Control Limit (LCL) = x̅ -k σ.The formula for calculating the average and standard deviation is presented in equations 2 and 3.

Selection of percentile values from anthropometric dimensions
Percentile is a certain percentage of a group of people with a size below or at that value.
The percentile calculation formula is presented in Equation 4. (4)

Musculoskeletal disorder (MSDs) operator complaint analysis
The analysis of MSD complaints using the Nordic Body Map (NBM) was used to identify and assess the pain complaints experienced by workers.MSD complaints can be determined through a questionnaire that includes various types of MSD complaints on a human body map.This questionnaire identifies muscle areas experiencing complaints, with levels of pain ranging from No Pain, Slight Pain, Pain, to Severe Pain.The results of the NBM can estimate the types and levels of complaints, fatigue, and discomfort in the muscle areas experienced by workers by examining and analyzing the body map derived from the NBM questionnaire, ranging from discomfort to severe pain [14].

Design (anthropometry) evaluation and improvement
Evaluation is carried out by analyzing the existing extruder design based on operator anthropometric data.Machine repair begins with designing technical drawings (with SolidWorks 2021) and making a new extruder prototype.

Determining the number of respondents/tool operators
Anthropometric measurements were conducted on 14 selected respondents who had previous experience as operators operating the extruder, consisting of 8 males and 6 females.The age of the respondents ranged from 16 to 58 years.Anthropometric data were collected in static conditions, considering the working postures while standing and operating the extruder.According to Erliana and Razif (2017), the static anthropometric dimensions related to the working posture of machine operation include D1, D2, D3, D4, D23, D24, D25, and D26 [15].Anthropometric dimension of extruder operators shows in table 2. To obtain valid anthropometric data, the next step is to test the adequacy and uniformity of the data.

Testing of adequacy data
An example is the calculation of data adequacy (95% confidence level and 5% accuracy level) for D1 anthropometry, as well as other data.Data is adequate if the amount of data required (N') is less than the amount of data (N).The results of the data adequacy test can be seen in Table 3. Table 3 shows the amount of data needed (N') and the amount of data (N).the number of D1 data required is 4.12 and the data collected is 14, therefore the D1 data is sufficient.Anthropometric data for D2, D3, D4, D23, D24, D25, D26 are considered adequate, because N' < N.

Uniformity test for D1
For example, testing the uniformity of data on the anthropometric code D1.This is followed by other data.Figure 1 shows that the overall data for D1 is uniform because it is within the upper control limit (UCL) and lower control limit (LCL).
The results of testing the uniformity of anthropometric data are presented in table 4 Based on Table 4, it is known that all dimensions are uniform.The average value of each dimension within the upper and lower limits.

Selection of percentile values from anthropometric dimensions
The selection of anthropometric dimension percentiles adjusts to the user's body size.Percentiles consist of large percentiles (90th, 95th or 99th), average (50th) and small percentiles (1th, 5th or 10th) [13].Machine design in this study uses a small percentile (10th), which means that the size used to design the machine is a small population size from anthropometric dimensions.10th percentile so that the extruder can be used by users with small body sizes.The percentile values for each anthropometric dimension are presented in Table 5.The selection of percentiles for each dimension follows the extruder design requirements, shown in Table 6.Height of the barrel D4 10th In Table 5, the height of the set box is determined using the anthropometric dimension D4a (vertical height from the floor to the right elbow) [7].The height of the set box is adjusted based on the anthropometric vertical height from the floor to the right elbow to ensure that the operator can reach and press/rotate the buttons to turn on and set the machine.The data consider the right side of the body as the dominant hand in occupational activities [16].The height of the noodle dies is also determined using the anthropometric dimension D4a at the 10th percentile to allow the forearm to easily lift the screw when inserting it into the barrel, thus reducing physical load.The appropriate height of the dies facilitates manual noodle cutting with scissors.The height of the hopper is determined using the anthropometric dimension D4a (vertical height from the floor to the right elbow).Erliana and Razif (2017) designed a rice grinding machine's hopper height to align with a person's standing elbow height [15].The height of the hopper is adjusted based on the anthropometric vertical height from the floor to the right elbow to enable the operator to input materials easily into the hopper inlet.According to Tarwaka et al. (2004), a lower lifting angle of the hand reduces discomfort and physical load [17].Unnatural working postures can lead to fatigue due to an increased workload.Based on the NBM questionnaire results, it is known that the extruder operator complains of stiffness in several parts of the body, including the upper neck, right shoulder, upper arm of the right hand, left calf, and right calf.From Table 7, it is observed that the highest level of stiffness complaint reported by the operator is in the right shoulder.The level of stiffness complaint in the right shoulder is described as pain after work, experienced several times a day.The complaint in the right shoulder is suspected to be caused by an ergonomic deficiency in the work posture, specifically the elevation of the right shoulder during the material feeding process in the extruder hopper.The arm is raised approximately 50 degrees above its natural position during the material feeding into the hopper.

MSDs (musculosceletal disorder) operator complaint analysis
The operator also complains of stiffness in the upper arm of the right hand as a result of the aforementioned work posture.This work posture arises because the height of the extruder hopper is higher than the operator's elbow, leading to post-work stiffness.The shoulder and arm are raised approximately 50 degrees from their natural position.The operator's hand has to repeatedly work by gradually feeding the material into the hopper until all the material is inside the barrel and pushed by the screw to be extruded.
The level of stiffness complaint in the arm is not as severe as in the shoulder because the arm can lean on the hopper during the material feeding process.Nilamsari and Innafin (2022) reported that work primarily involving hand use can cause shoulder and arm pain [10].Repeated pushing (inserting) of material, a relatively long duration of work, and physical strain can lead to complaints of stiffness and pain after work.
The slight pain and stiffness felt in the upper neck region are suspected to be caused by a work posture involving downward bending of the neck at an angle of 70 degrees when setting the extruder (head bending while pressing the tool setting button), bowing at an angle of 45 degrees during screw and dies installation, and bowing at an angle of 35 degrees during the material feeding process in the extruder hopper.
According to the NBM, the operator also complains of stiffness in the right and left calves.These stiffnesses are likely due to the standing work posture.Standing work posture that relies on both legs for a prolonged period and stationary positions has the potential to cause stiffness in the calf muscles.This aligns with Bridger's (2003) findings that risky work postures (e.g.standing, bending, lifting, carrying, and pulling loads) can lead to MSDs or muscle complaints [18].

Evaluating machine design with anthropometry
Occupation is one of the factors that influence the occurrence of health complaints.Manual work is a potential and higher risk factor for musculoskeletal complaints [19].This study analyzes the ergonomic risks of operating a non-wheat noodle extruder or mould machine.The operation process of the machine begins with installing the screw and dies into the barrel, followed by starting the machine and inserting the material into the hopper's inlet.The operator gradually feeds the material into the machine, which is then processed in the screw until it is pushed through the dies and formed into noodle strands.The material feeding process is still done manually, with the operator pushing the dough gradually into the hole in the hopper.
Extruder plays a vital role in the production process of non-wheat noodles.The production of non-wheat noodles requires a different process because non-wheat flour has no elastic gluten properties.The production process of non-wheat noodles begins with steaming the flour dough mixed with a salt solution to facilitate starch gelatinization/granule breakdown.After steaming, the dough is fed into the extruder machine for the extrusion and moulding processes to form noodle strands [20].Figure 2 depicts a non-wheat noodle moulding machine prototype, specifically a single-screw extruder.The main components of the extruder include the driving system, feeding system, screw, heating jacket, die, and control system.The specifications of the extruder prototype include a 3.77 kW motor power, a 502 mm screw length, and a 12 kg/h capacity.The operation procedure of the extruder machine consists of machine setup, operation, and finishing.During the machine setup stage, the screw and dies are installed into the barrel, with the hopper positioned above the barrel.Subsequently, the machine is switched on, and the material is fed into the hopper.Then, the screw pushes and kneads the dough, causing it to extrude through the die into lengthy strands of noodle dough.Based on the operator's working posture, it can be observed that there is a bent back posture when starting the machine and adjusting the temperature.Bowing at an angle of 60 degrees results in the head and neck tilting downward by almost 70 degrees.While bowing, the upper wrist is lifted by 20 degrees to press the power button.This is presumably because the dimensions of the machine are not in accordance with anthropometry.The on/off power button height and temperature settings range from 46-65 cm from the floor.The time required to start and adjust the machine is 2-4 minutes.This position is only at the beginning and end of the work.According to Tarwaka et al. (2004), a bent back posture is unnatural and poses a risk of MSD (Musculoskeletal Disorders) injuries [17].
Nilamsari and Innafin (2022) reported that work postures that trigger MSD complaints include a bent torso, bent knees, and wrists holding a load [10].In the setting box, it can be seen that the power button is positioned at the lowest point, while the indicator light is located above the power button.This requires the operator to reach further down to press the power button.Based on Mayasti et al. (2023) stating that a setting box that is too low creates an uncomfortable working posture [7], we recommend changing the position of the box panel.
In Figure 3, it can also be seen that the operator's elbows are raised.This is presumably because the height of the hopper is 110.5 cm, relatively higher than the operator's elbow of 92 cm.In this working posture, the operator's hand must push the material into the hopper hole continuously.Too high a hopper can cause shoulder injury [15].

Design improvements
The evaluation of the non-wheat noodle-making machine (extruder) design aims to assess the existing design and make improvements based on operator/user anthropometric data.The design improvements are carried out to minimize the risk of MSDs injuries.Based on NBM, the operator complains about stiffness in the upper neck, shoulder, upper arm of the right hand, and left and right calves.These complaints are suspected to be caused by an ergonomic deficiency in the work posture due to machine dimensions that do not meet the operator's anthropometric requirements.The dimensions of the extruder machine that require improvement include the height of the hopper, the height of the lock and dies, and the height of the control box.The design improvements of the extruder based on anthropometry can be seen in Table 8.Table 8 shows that the existing setting buttons on the extruder are 46 and 54 cm from the floor.Based on anthropometric studies, it is recommended to set the height of the setting button at shoulder height.At this height, the operator stands with their shoulder and arm extended forward to press the buttons.The height of the temperature adjuster is 120 cm, in line with the research of Mayasti et al. (2023), which improved the design of a cabinet dryer based on anthropometry.The height of the set box is adjusted to the dimension of anthropometric D3, which is the height of the arm shoulder hand at 123.3 cm so that the machine setting can be done without having to squat [7].Erliana and Razif (2017) mentioned that a hopper that is too high could cause fatigue in the shoulder and hand.Therefore, the recommended design improvement is to adjust it to the anthropometric height of the standing elbow, which is 92 cm [15].
The height of the locking mechanism and the dies on the existing extruder are 110 cm and 100 cm, respectively.Therefore, it is recommended to set them maximum at 92 cm (standing elbow height).According to the operator's anthropometry, the appropriate height of the locking mechanism will facilitate the hand when locking the dies.The dimensions of the existing extruder caused the hand to be lifted higher and the physical load to be higher than the suggested improvement.Bridger (2003) stated that the position of the raised and pushing/receiving load hand poses a risk of MSDs injuries [18].The width of the existing extruder of 85 cm is close to the anthropometric width range of the right and left elbows, which is 70 cm.Considering the aforementioned anthropometrics, Figure 4 shows the extruder with new features and dimensions.

Conclusions
Based on the evaluation of the non-wheat noodle extruder machine design, it is known that the operator's working posture poses a risk of MSDs.Analysis of muscle complaints using NBM reveals that the operator experiences stiffness in the upper neck, right shoulder, upper arm of the right hand, left calf, and right calf.When feeding materials into the hopper, the operator's working posture is ergonomically inadequate due to the arm's raised and repetitive pushing motion while feeding the materials.The evaluation of the machine design based on anthropometric dimensions suggests several improvements.The design improvements of the extruder machine include changes in the height of the footstep to 27.7 cm.Changes in footstep height create ergonomic work postures, including the height of the hopper above the footstep of 92.1 cm adjusted for standing elbow height and the height of the setting button to 120.95 cm from the footstep, which can be rotated, adjusted for standing shoulder height.The operator's posture when operating the new prototype no longer involves bending when adjusting the machine, and the elbows can lean on the hopper while feeding materials.

D2b from the floor
to the outer corner of the left eye.D3a from the floor to the top of the right shoulder.D3b from the floor to the top of the left shoulder.D4a from the floor to the lowest point at the right elbow angle.D4b from the floor to the lowest point at the left elbow angle.D23a from the back of the right elbow to the tip of the middle finger.D23b from the back of the right elbow to the tip of the left finger.D24a from the top of the right shoulder to the tip of the middle finger of the right hand, with the right elbow and wrist straight.D24b = the standard deviation; = sum of Xi; and = sum of average x; n = ∑  ∑  number of samples; k : confidence level of the index coefficient

Fig. 2
Fig. 2 Two-dimensional technical drawing and the prototype of the existing extruder machine.

Fig. 4
Fig.4 The improvement in the design of the extruder machine based on anthropometry: 2D technical drawing.

Figure 4
Figure 4 is a 2D design of the extruder improvement based on anthropometric principles.Footstep height changed from 15.5 cm to 27.7 cm.The design improvements include changes in the height of the control panel box to the height of standing shoulders, which is 120.95 cm from the footstep.The height of the hopper from the footstep is set to the height of the elbow, which is 92.1 cm.The height of the lock and dies is set to the elbow height, which is 92.1 cm from the floor.

Fig. 5
Fig.5 The prototype of the improvements extruder machine A prototype of the extruder design improvements can be seen in Figure5.It can be observed that the control panel box can be rotated, eliminating bowing when adjusting the machine.The outcomes of the examination of the posture in the new extruder are displayed in Figure6.Operators no longer have to bow over when setting up the extruder.The panel box for machine adjustments (temperature setting, screw, heater, and blower) is positioned at 120.95 cm from the footstep.This improvement makes it simpler for the hand to reach when standing, eliminating the need for a bent back and improving vision.It is also easier to modify the machine because the panel box can swivel 360 degrees.The footstep is placed at a height of 27.7 cm to guarantee that the operator can easily reach the elbows' height of 92.1 cm when standing and loading ingredients into the hopper.The new extruder dies' height has been modified to correspond to anthropometric dimension D3, 92.1 cm from the floor.The operator may conveniently unlock and open the dies from this height and remove the screw from the extruder barrel.

Fig. 6
Fig. 6 Working posture with the new design extruder.

Table 1 .
Distance of each anthropometric dimension

Table 2 .
Anthropometric dimension of extruder operators

Table 3 .
Data adequacy test

Table 6 .
Determination of percentiles of machine dimensions

Table 8 .
Design improvement