Keywords

1 Introduction

In this practical research that is a further study of ‘A Study of Usability Design of Baren Products’ [1], a design practice of baren product usability has been conducted, which is the design of product form. The external form design of the product needs to start from the shape, color and material of the product, find the corresponding points of the factors affecting the usability, get specific design elements, and truly transform baren product usability requirements into product language to complete the design practice. The use of curve shape in the form design of the product can better meet the demand for hand semi-clenched fist and hand comfort, which is not only fashionable with modern sense but also warm with simple life, and more in line with the modern society’s pursuit of spiritual and emotional level [2], but also better meet the hand comfort demand.

In baren product design, the selection of materials follows several key principles.

  1. 1)

    Aesthetic principle: consider whether the sensory characteristics of materials conform to the emotional transmission of products to users.

  2. 2)

    Principle of usability: the function of baren determines that the material should be wear-resistant material. In order to maximize the transmission of the operator’s arm power to the tool, it is necessary to consider how to avoid the skid resistance of the interactive interface and reduce the pressure of the operator’s hand muscles.

  3. 3)

    Principle of technology: in this study, the plastic forming process and the injection molding process of silicone are relatively mature production processes in the market, and the connection between the plastic and silicone is a breakthrough point.

  4. 4)

    Economic principle: try to choose materials with low price but good processing performance, so as to produce products with good texture, and the price positioning is more suitable for the consumption level of college students.

Through the above analysis and review of the literature related materials, it is finally determined that the baren chassis is made of ABS plastic which supports various processing methods, good surface gloss, heat resistance and wear resistance. Then, the surface of the baren handle can be designed with a non-slip pattern or a handle sleeve, and the handle sleeve is made of a soft rubber material, which can enhance the product feel and increase the operation comfort.

2 Baren Product Design Practice

The design of the scheme integrates the ease of use attributes summarized in the previous article ‘A Study of Usability Design of Baren Products’ [1], the factors affecting the usability, and the specific design elements reflected in the product design, etc. The main design factors summarized in the previous article should be referred to at any time in the design of the product scheme as follows:

  1. 1.

    The hand is the most comfortable when it is half held. When designing the shape of the handle, try to consider the most comfortable shape when the hand is operated;

  2. 2.

    How to make the modeling simple and soft with a certain flowing curve.

  3. 3.

    The shape of the product can intuitively guide the user’s holding and make the area with more muscles in the hand become the main application point of man-machine contact surface.

Following these design elements, the drawn design scheme is as shown in Fig. 1.

Fig. 1.
figure 1

Baren product design concept renderings.

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The innovative features of the new baren products are as follows, as shown in Fig. 2:

Fig. 2.
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Interaction diagram of baren product design concept.

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  1. 1.

    The handle structure changes the way of holding the existing engraving rubbing tool. The inclined handle is adopted to make the hand in a semi-clenched state. It eliminates the pain caused by the back of finger contact with the chassis;

  2. 2.

    Since the application point is placed on the thenar and hypothenar muscles, it reduces the contact force on sensitive parts of the hand, such as the palm of the hand, and reduces the local pain intensity of the hand;

  3. 3.

    The upper surface of the baren chassis was made into an inclined surface, where the upper surface of the force applying end close to the wrist was of a high vertical height, making the bending angle between the forearm and the palm of the wrist joint become smaller when rubbing, reducing the pressure on the wrist joint and improving the hand comfort in the rubbing process;

  4. 4.

    Change the curvature of the edge of the chassis, compared with the existing plastic baren, reduce the chance of puncture the paper and poke the finger;

  5. 5.

    The large area connection structure between the handle and the chassis makes the pressure distribution at the bottom of the chassis more even than the existing plastic baren;

  6. 6.

    The contact area between thumb and pinky is covered with silicone pads to improve the anti-skid and comfort performance;

  7. 7.

    Baren is generally divided into two parts: the main body of the handle and the main body of the chassis.

The two parts are bonded by the special adhesive for ABS engineering plastics, wherein the structure of the upper and lower buckles increases the stability of the component connection.

In the previous research ‘A Study of Usability Design of Baren Products’ [1], by referring to the hand size of Chinese people and combining with the relevant product size calculation formula, the optimal recommended length range of baren product holding area is 97 mm to 103 mm. The value of handle holding area of this product scheme is 100 mm, which is within the recommended range and meets the requirements. The recommended width range of the massage chassis of baren product should be greater than 92 mm and less than 105 mm. The width size of the chassis of this scheme should be set at 100 mm. Baren chassis length need to be in 105 mm to 174 mm, if given the length and width of the golden ratio relations will be more conform to the requirements of the beautiful, the golden ratio is 0.618:1, as shown in Fig. 3, through calculation, it is concluded that conform to the golden ratio chassis size is about 162 mm in length, with a value within the scope of the suggested size, so the baren product with such size more in line with the size characteristics of the hand.

Fig. 3.
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Product specification of baren product design concept.

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The processing technology of baren product adopts injection molding. In order to facilitate processing and production, the product is designed as two big shell structures, the handle body and the chassis body, as shown in Fig. 4. The shell structure is about 2.5 mm thick, which not only saves structural materials, but also has good spatial force transfer performance and pressure bearing performance, as shown in Fig. 5.

Fig. 4.
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Structure exploded view of baren product design concept.

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Fig. 5.
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3D printing model diagram of baren product design concept.

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3 Usability Test of the New Design of Baren Product

The baren product used as a comparative test is ABS plastic disc baren and wood mushroom made in China. It is the most commonly used baren product for primary printmaking students, and the plastic baren is a representative product that causes longitudinal bending of the wrist when rubbing, the wood mushroom is a representative product that causes the lateral bending of the wrist joint when rubbing. The two grip** methods caused by these two products are relatively representative, so they are selected as research objects.

Ten college students with experience in lithography were recruited. The student testers had no diseases or injuries in their hands, no muscle fatigue before the experiment, and all had the experience of using baren lithography. The participants are numbered from No. 1 to No. 10, with measuring and recording the participants of the hand basic human body size, in the process of use baren print version. The main human palm size have hands long, wide, so in accordance with the requirements of surveying, testing and record these indicators, which conforms to China’s national per capita 10 adult body size standards.

3.1 Comparative Test Analysis of Hand Joint Activity

When the arm applies the same force to the wrist, the new bare and plastic bare, their product chassis has the same pressure on the imprinted board, but the smaller the angle between the wrist and its bearing plane, the less laborious the wrist joint. Obviously the angle A is smaller than the angle C, so the new baren is slightly better than the plastic baren in terms of the longitudinal joint degree of the wrist. Therefore, if the same force is applied to the product, the pressure and damage of the wooden mushroom’s wrist joints are greater, as shown in Fig. 6.

Fig. 6.
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Hand joint activity test diagram.

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3.2 Right Arm Fatigue Test

The printing of printmaking is divided into multiple processes. The most tiring one is the process of engraving. After the engraving is completed, it needs to be painted with pigments, and the final color is followed by the process of rubbing. Then, during the process of engraving, the muscles will continue to contract. As the marking time continues, the muscles will enter a state of fatigue and begin to fail to output the required force [3]. By calculating the reduction of the right arm grip strength to understand the user’s right arm fatigue change, the right arm fatigue index is used to evaluate whether the new baren product handle is easier to grasp.

In the right arm fatigue test of this subject, the tester needs to use the dynamometer to measure the maximum grip force value and record it before using the different baren products for rubbing, and then start the baren rubbing process for 10 min, and the rest interval of each experiment is 30 min. The subject needs to be rubbed along the provided rubbed road map during the experiment. The length and width of the rubbing path are the same as the A4 layout size, as shown in Fig. 7. A horizontal rubbing action or a vertical rubbing action is required every second, and a total of 600 rubbings are completed. After finishing the rubbing, you need to immediately measure the maximum grip strength with a dynamometer and record. Finally, the reduction of the right arm grip strength is calculated, and the experimental results are compared and analyzed. The brand of electronic grip dynamometer for testing is **angshan, model EH101. When the subject continues to apply force for three times, it can automatically give the maximum grip strength after three grips, as shown in Fig. 8.

Fig. 7.
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Roadmap for rubbing operation.

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Fig. 8.
figure 8

Electronic grip dynamometer for testing.

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Figure 9 lists the amount of grip reduction of the experimenter after 600 rubbing actions. Before the start of the experiment, the average value of the maximum right arm grip strength of the 10 subjects was 28.3 kg, and the standard deviation was 8.33 kg. After 600 rubbing movements, the average reduction of the right arm grip force (8.25%) caused by the new bare solution is much smaller than the average of the grip strength of the original ordinary plastic baren and wood mushrooms, indicating that the new baren handle design is more suitable for users, indirectly verified that the research framework based on usability analysis is effective in the design of new baren products. The specific test results are shown in Table 1.

Fig. 9.
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Comparison of the reduction of grip strength before and after the user uses different baren.

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Table 1. Right arm grip analysis of users using different types of baren.
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3.3 Subjective Comfort and Satisfaction of Users

In addition to the objective fatigue index test, users who participate in the test are required to score the comfort of the new baren product to comprehensively analyze and evaluate whether the handle of the new baren product is easy to hold. The overall score is above 8 points, as shown in Table 2, indicating that the product basically meets the user’s recognition of the need of easy grip. There are a few individual users who are not very satisfied with the comfort of the rubbing process. The reason is that although it feels very good to use, it is psychologically uncomfortable, because it feels that the appearance of the product changes greatly, and the psychological needs to adapt. Based on these questions, we will discuss how to improve at the end of the article.

Table 2. Evaluation results of users’ subjective comfort and satisfaction.
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3.4 Subjective Psychological Preference of Users

Table 3 lists the experimental participants’ psychological preference for the three bare products. Quantitative assessment of the participants’ psychological preference for each type of bare product requires the experimenter to choose the type they like (multiple choices are possible) and to justify their reasons. Analysis of these reasons can be drawn: most of the experimenters are very fond of the new plastic baren, because the new product looks more fashionable, people are willing to use, more personalized curve modelling, in use process, easy to grasp and more labor-saving. Individuals who are not optimistic think that they are worried about low product awareness and have a sense of disengagement from other tools of printmaking. There are also very few users who have large palms and long fingers, which makes the hand ball muscle unable to grip on the handle groove comfortably. Some users with long fingers simply do not bend their fingers to grasp, can also achieve the requirements of comfort. Half of the users are not very fond of the original plastic baren products (50%). The main reason is that compared with the new baren, there will be more problems in the process of use, such as fatigue, clenching, etc., in short, it is not very useful. Only a small number of users like wood mushrooms, because first of all, the quality of wood mushrooms on the market is not uniform, and some magic mushrooms look very textureless, the surface is not smooth, and the function is relatively simple. The main reasons why the experimenters like the new baren product are as follows: compared with the original baren product, the holding part of the baren product is designed in a more reasonable way, which is more consistent with manual operation, the product interaction is improved, and the product form is more attractive. This is consistent with the conclusion in the second chapter that the handle of baren product is easy to hold, the product interaction is clear and easy to understand, and the good emotional experience, which verifies the effectiveness of the usability attribute.

Table 3. Results of psychological preference survey.
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3.5 Assessment Revision and Outcome Transformation

In summary, the new baren overall usability evaluation result was good, but some users with larger palms reflect the unreasonable groove design of the new baren product handle, the groove depth and width cannot meet the finger comparison. In order to make the products more universal and better meet the needs of more people, the long user has further optimized the handle parts of the baren product solution. The overall recess depth of the groove portion of the bare product handle in the original solution is reduced, making it more suitable for users of different finger lengths. The new bare model was used for retesting, as shown in Fig. 10. The results of the evaluation showed that users of different hand lengths reflected the grip comfort and could well meet the grip requirements of different users.

Fig. 10.
figure 10

The final baren design product.

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4 Conclusion

After the research of the subject, the follow-up will try to promote this new type of baren and put it into the market. In order to protect the research results, it has applied for a utility model patent. Before the marketization of the product, the production cost needs to be estimated. The previous interview results on the price show that the highest price range acceptable to the primary users is 30–60 yuan; the highest price range acceptable to the senior students is 50–200 yuan. As both the new baren main material and the existing plastic baren material are made of ABS engineering plastics and the processing technology is injection molding, the price of the new baren can be estimated by referring to the amount of materials. The existing plastic baren weighs about 87 grams, and the new plastic baren model weighs about 225 grams, with a weight ratio of about 1:2.5. The market price of the existing plastic baren is about 9 yuan. Considering that the new baren will use a small amount of silicone. Therefore, the price ratio is estimated to be 1:3, and the new baren price is about 30 yuan, which is consistent with the previous price survey results.

In this paper, the research and design of baren products innovatively introduces usability analysis into the design research of baren. Focusing on the usability of plastic baren, redesigning a new baren that meets the needs of usability and has a good product interaction experience is of great significance for the theoretical innovation of baren products and the development of new markets.

This topic introduces the concept of usability for the design and research of new baren products, and has the following results:

  1. (1)

    Through market research, pre-interview and observation method, the problems of baren products at home and abroad are summarized. After analysis, the user’s usability for baren products is summarized.

  2. (2)

    Multi-dimensional analysis of the factors affecting the usability of baren products, combined with the basic design elements of the product, summed up the product design practice process framework based on usability.

  3. (3)

    Through the induction of the usability requirements, the factors affecting the usability are analyzed, and finally a new baren product that satisfies the target users is designed.

The target users of this project are university students, so the new baren designed is mainly aimed at the university market. However, the age distribution of baren’s user groups is relatively broad, and the needs of different age groups are also different. Therefore, when designing baren’s products, designers should conduct targeted and systematic analysis of the target users.

In the design investigation stage, the elements of easy storage, universality and easy cleaning analyzed from the perspective of the use environment were not expanded in depth in the following text, which led to the feedback from users in the evaluation stage, feeling that the newly designed baren was a little abrupt in the engraving tool. There is also a need for a systematic redesign of the entire printmaking tool, or for them to come up with something to store.

This research mainly considers the operation habits of most right-handed users, and does not consider the situation that some users are left-handed. Generally speaking, there is little difference in the use of power between the left hand and the right hand, except that the ways of holding the product and the direction of movement during operation are different. If baren products are to be industrialized with the printmaking industry, these unique factors need to be considered in the development process, and thoughtful and in-depth research or individual design is needed.