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The problem lies in the quality of the umbrella nails for asbestos or zinc roofs which often experience damage to the nail head is not large enough, the tip of the nail is blunt, thus damaging the roof material, and susceptibility to corrosion due to weather, and slow manual production. The purpose of making is to obtain umbrella nails with a length of 50 mm and a diameter of 2.5 mm which are strong, pointed tips, relatively fast. The manufacturing method includes: making cylindrical umbrella pieces from 2 mm thick aluminum with a diameter of 25 mm and a 1.5 mm hole center, selecting raw materials for low carbon steel wire, AISI 1020 in the form of a 3 mm diameter coil, straightening and reducing the cross-section of wire using a die (wire drawing),, forming the nail head (cold heading), mechanically cutting the pointed end, forming the nail umbrella from cylindrical pieces that have been inserted with 50 mm long nails and pressed, immersing the umbrella nails in 500oC zinc liquid (galvanizing) for 2 minutes, checking dimensions and quality standards. The manufacturing results are in the form of strong zinc-coated thumbtacks measuring 50 mm in length, 2.5 mm in diameter, 1.2 mm in thickness of the thumbtack plate, total production cost of IDR 340/unit, and process duration of 12 seconds/unit, which implies that the need for strong and corrosion-resistant thumbtacks can be met for various related engineering needs.

The problem lies in the load lock from the wheel arm, the BLDC motor whose distance cannot be adjusted, and the flywheel whose movement is less smooth than the original design. The purpose of refining the design is to obtain smooth movement and the position of the load lock from the wheel arm, the BLDC motor that can be adjusted to be ergonomic and optimal. The method of refining the design and manufacture of the rear shock breaker spring type electric bicycle through the stages of working load analysis, the need for the distance of the load setting position and the BLDC motor, calculating the construction strength, manufacturing components, assembling components, and evaluating the results of the shock breaker manufacture. The results of refining the design and manufacture of the rear shock breaker spring type electric bicycle show that the movement of the load lock position from the wheel arm and the BLDC motor is smooth, the flywheel must be balanced, the dimensions of the shock breaker device are 120 cm long, 49.5 cm wide, 155 cm high, 120 rpm rotation speed, 2 cm shock breaker movement distance, and 1.5 cm sideways movement deviation which implies being able to provide adequate damping for electric bicycle riders well.

The unknown exact flexural strength of low carbon steel, Randu ribs wood, paving stones, and lightweight bricks is a problem faced. The purpose of this research is to obtain the flexural strength of low carbon steel, Randu ribs, paving stones, and lightweight bricks. The research method is carried out through the preparation of low carbon steel specimens 16mmx200mm, Randu ribs 40mmx60mmx250mm, paving stones 55mmx100mmx200mm, lightweight bricks 95mmx100mmx300mm, Tarno Grocky flexural testing machine settings, flexural testing support distance for low carbon steel 160mm, Randu ribs 220mm, paving stones 170mm, and lightweight bricks 260mm, flexural testing of each material, making flexural stress and deflection curves for low carbon steel, and analyzing flexural test results. The results of the study showed that the flexural strength of low carbon steel was 698 MPa at a deflection of 1.1 mm, the flexural strength of Randu rib wood in an upright position was 40.7 MPa, in a horizontal position was 55.5 MPa, in a normal position of paving stone in an upper position (normal) was 6.64 MPa, in a lower position (upside down) was 6.62 MPa, and in a lightweight brick was 1.28 MPa, which implies that the type of material, the distance between supports and the cross-section of the specimen greatly affect its flexural strength, except for ductile materials for low carbon steel which do not have flexural strength, but have yield strength at a certain deflection.

The unknown exact tensile strength of cylindrical cross-section carbon steel and rectangular cross-section carbon steel is a problem faced. The purpose of the research is to obtain the tensile strength of cylindrical cross-section carbon steel and rectangular cross-section carbon steel. The research method is carried out by turning carbon steel specimens to a diameter of 7.92mm, a length of 200mm and milling carbon steel cross-sections with a width of 12mm, a thickness of 4mm, setting the Tarno Grocky tensile testing machine, clamping both ends of the specimen with grips, tensile testing until the specimen breaks, measuring the gauge length after the specimen breaks and is properly cupped again, making stress and strain curves, and analyzing the tensile test results. The test results show that the tensile strength of carbon steel with a cylindrical cross-section is 554 MPa at a strain of 3.86%, the yield strength is 514 MPa at a strain of 3.06% and the tensile strength of carbon steel with a rectangular cross-section is 712 MPa at a strain of 2.45% and the yield strength is 487 MPa at a strain of 0.59%, which implies that both steels are ductilely broken, due to shrinkage. cross-section (necking) which includes ST 60 because the yield strength is more than 360 MPa.

Problems in the transmission box of the Drilling Machine 438-02-814-0925 type (0.75 HP, 230/400V, 1425 rpm, produced in 1988) are the degradation of mechanical components for the pulley, V-belt, and rolling bearing. The purpose of maintenance and repair planning is to obtain maintenance costs, maintenance schedules in the period 2026, and the ratio of maintenance costs to profits. The maintenance and repair planning method includes collecting previous maintenance data; application of the inspection-replace-repair-overhaul (IRRO) method; evaluation of the working conditions of components, especially on the pulley, V-belt, spindle pulley (driven pulley), and rolling bearing; prediction of component service life; prediction of repairman costs; prediction of supporting equipment that will be used in maintenance; prediction of spare part replacement time or reinstallation of components after repair; estimation of maintenance and repair costs in 2026; and calculation of the ratio of maintenance costs to profits. The results of maintenance and repair planning obtained maintenance costs in 2026 amounting to Rp 4,627,000 with an estimated Drilling Machine rental rate of Rp 75,000/hour which has the opportunity to be rented for 400 hours/year, and a maintenance cost to profit ratio of 15.42% which implies that the Drilling Machine still has the opportunity to generate profits and is suitable for use in the coming years.

The problems encountered are damage to the rubber wheel mount and universal/cross joints on the 90 m/hour capacity wood profile making machine, which can affect the uniformity and speed of wood profile making. Maintenance and repair planning aims to be able to create a maintenance and repair schedule for the 90 m/hour capacity wood profile making machine for the period 2026, estimate maintenance costs and the ratio of maintenance and repair costs to machine profits. The maintenance planning method includes collecting maintenance data from previous maintenance periods, reviewing the specifications of the wood profile making machine, estimating the age and price of components that are estimated to be damaged, estimating the cost and duration of dismantling and installing components that have been repaired in accordance with the provisions of the requirements for usable components or replacement spare parts, scheduling maintenance and repairs, estimating maintenance and repair costs for the period 2026, and determining the ratio of maintenance costs to profits. The planning results in the form of a maintenance-repair schedule for the period 2026; maintenance and repair costs in 2026, the ratio of maintenance costs to profits, and their implications indicate that the machine is still prospective and usable.

Unexpected downtime of a 2 kg/hour coffee grinder is crucial in cafe operations, thus less guaranteeing the availability of the grinder. The purpose of component replacement and repair planning is to obtain a prediction of the maintenance and repair schedule and costs in the 2026 period. The component replacement planning method includes collecting previous maintenance and repair data, applying the inspection-replace-repair-overhaul (IRRO) method, assessing component conditions, predicting component life, predicting technician costs, predicting supporting work equipment and supporting materials to be used in maintenance, predicting the time to replace spare parts or reinstall components after repair, estimating maintenance and repair costs for the 2026 period, and calculating the ratio of maintenance costs to profits. The results of component replacement and repair planning obtained maintenance costs for the 2026 period are IDR 2,350,000, - with an estimated coffee grinder rental rate of IDR 25,000/hour which has the potential to be rented for 1440 hours/year, and the ratio of maintenance costs to profits is 6.5% which implies that the coffee grinder with a capacity of 2 kg / hour is still suitable for use for the next few years and still has the opportunity to make a profit.

The problem with a passenger car with a capacity of 15 people lies in its unscheduled maintenance and having broken down on the road. The purpose of component replacement planning is to obtain component replacement costs, maintenance and repair schedules for the 2026 period, and the maintenance cost-to-profit ratio. The planning method includes collecting previous maintenance data, applying the inspection-replace-repair-overhaul (IRRO) method, evaluating component conditions, estimating component lifespan, estimating labor costs, estimating supporting equipment to be used in maintenance, estimating the time to replace spare parts or reinstall repaired components, estimating maintenance and repair costs for the 2026 period, and calculating the maintenance cost-to-profit ratio. The results of component replacement planning obtained costs for the 2026 period are IDR 11,780,000 with an estimated passenger car rental rate of IDR 800,000/24 ​​hours (day) which has the potential to be rented for 4,320 hours/year, and the ratio of maintenance costs to profits is 10.33% which implies that passenger cars with a capacity of 15 people are still prospective to generate profits and are suitable for use for the next few years.  

The problem with a 4-stroke gasoline engine-driven electric generator is a decrease in tool performance due to wear on important components for the stator, cooling fan, air filter, oil filter, and gasket. The purpose of component replacement planning is to obtain replacement costs, maintenance schedules in 2027, and the ratio of maintenance costs to profits. The component replacement planning method includes collecting maintenance data from previous years, applying the inspection-replace-repair-overhaul (IRRO) method, assessing component conditions, predicting component lifespan, predicting labor costs, predicting supporting equipment to be used in maintenance, predicting spare part replacement times, predicting maintenance costs in 2027, and calculating the ratio of maintenance costs to profits. The results of the replacement planning obtained maintenance costs in 2027 amounting to IDR 570,007,- with an estimated electric generator rental rate of IDR 30,000,-/hour which has the potential to be rented for 128 hours/year, a profit of IDR 3,840,000,- was obtained, and the ratio of maintenance costs to profits was 14.84% which implies that a 2.5 kW electric generator that uses gasoline-pertalite fuel of around 1.5 liters/hour at maximum power is still suitable for use in the next few years and has the potential to generate profits.

The decline in the performance of the die casting machine in 1998 after a long period of producing copper terminals showed dimensional defects and instability in product quality, especially in nozzle clogging, reduced copper flow, crust buildup on the gooseneck, plunger movement obstruction, and hydraulic pressure leaks. The purpose of planning the replacement and repair of die-casting machine components is to obtain replacement and repair costs, replacement and repair schedules for the period 2026, and the ratio of maintenance costs to profits. The replacement and repair planning method includes collecting previous maintenance data, applying the inspection-replace-repair-overhaul (IRRO) method, evaluating component conditions, predicting component service life, predicting labor costs, predicting supporting equipment to be used in maintenance, predicting the time to replace spare parts or reinstall repaired components, estimating replacement and repair costs for the period 2026, and calculating the ratio of replacement and repair costs to profits. The planning results obtained replacement and repair costs for the 2026 period are 75.770.000,- IDR with an estimated die casting machine rental rate of  1,500,000 IDR/hour which has the potential to be rented for 1,200 hours/year, and the ratio of maintenance costs to profits is 10,02 % which implies that the die casting machine with a capacity of 40 units/hour is still suitable for use and has the prospect of generating profits for the next few years.

The problem lies in the inconsistent quality of M10 hexagonal head bolts with a spacing of 1.5 mm, a bolt length of 100 mm and slow production speed for manual production. The purpose of the analysis is to obtain consistent, standard, and productive quality of M10 hexagonal head bolts with a spacing of 1.5 mm, a bolt length of 100 mm. The analysis method includes the selection of AISI 1040 raw materials with a diameter of 10 mm in the form of rolls, the determination of the production process through raw material inspection, diameter reduction from 10 mm to 9.8 mm, the formation of hexagonal heads with a machine, cutting the length of the bolts and the bolt end chamfer, making M10 threads with a range of 1.5 mm with a machine, hardening, 10 m thick Zinc coating, thread profile inspection, sample hardness test, and sample tensile test. The results of mass production with the machine obtained a hexagonal head bolt with a thread size of M10x1.5 mm, a bolt length of 100 mm, a capacity of 500 units/hour in accordance with the ISO 9001:2015 standard with a hardness of 30 HRC and a tensile strength of 830 MPa at a cost of Rp. 1133/bolt and a process duration of 8.3 minutes/bolt which implies that product quality can be more guaranteed to be consistent and uniform.

Waste from used Polypropylene (PP) and High Impact Polystyrene (HIPS) plastic is problematic in its management. The purpose of this research is to obtain the fatigue life of a mixture of used PP and HIPS plastics in its pure plastic. The research method is through the stages of mixing pure PP and 50% volume of used PP, pure HIPS and 50% volume of used HIPS, injection molding of R.R. Moore standard fatigue test specimens for pure PP, pure HIPS, pure PP + used PP, and pure HIPS + used HIPS, checking the straightness and smoothness of the molded specimen surface, fatigue testing with increasing serial loads, analysis of the bending stress curve (S) against fatigue life (N). The results showed that mixing used PP and used HIPS in pure plastic affected the fatigue life at the test speed (n)=2100 rpm for recycled PP was 9.84% shorter than pure PP, and at n=1600 rpm for recycled PP it was 9.32% shorter than pure PP, while at n=2100 rpm for recycled HIPS it was 4.45% shorter than pure HIPS, and at n=1600 rpm for recycled HIPS is 4.77% shorter than pure HIPS, while the fatigue life of pure PP is 1627704 cycles and the fatigue life of pure HIPS is 1291636 cycles or the fatigue life of pure HIPS is 20.65% shorter than pure PP, the implication of which is that the addition of used PP and used HIPS reduces the fatigue life to 9.84% for PP and 4.45% for HIPS.

The problem faced is the decline in the performance of a 650 liter/minute centrifugal pump due to wear on components, especially the impeller, rolling bearings, and mechanical seals in supplying process water and clean water in industrial production systems. The planning objective is to obtain a maintenance schedule for a 650 liter/minute centrifugal pump for the operational period of 2026 and the ratio between maintenance costs and profits generated by the machine. The maintenance planning method includes collecting maintenance data from previous maintenance periods, reviewing centrifugal pump specifications, applying the inspection, replace, repair, and overhaul (IRRO) approach, estimating the age and price of components that are expected to be damaged, estimating the cost and duration of dismantling and installing components that have been repaired in accordance with the provisions of the requirements for usable components or replacement parts, scheduling maintenance and repairs, estimating maintenance and repair costs for the 2026 period, and determining the ratio of maintenance costs to profits. The planning results are in the form of a maintenance schedule for the 2026 period worth IDR 4,290,000,-, a maintenance cost to profit ratio of 7.44% and the implications indicate that the machine is still suitable for use and prospective for operations in the next few years.  

The problem with the coconut grater machine is that the machine has decreased performance after being used for several years, especially in the mechanical components (electric motor, V belt, Pulley, grater knife, hopper) and its electricity. The purpose of maintenance and repair planning is to obtain costs, maintenance and repair schedules for the period 2026, and the ratio of maintenance costs to profit. The maintenance and repair planning method includes collecting previous maintenance data, applying the inspection-replace-repair-overhaul (IRRO) method, evaluating component conditions, predicting component lifespan, predicting labor costs, predicting supporting equipment that will be used in maintenance, predicting the time to replace spare parts or reinstall repaired components, estimating maintenance and repair costs for the 2026 period, and calculating the maintenance cost to profit ratio. The results of maintenance and repair planning obtained maintenance costs for the 2026 period were IDR 957,000 with an estimated coconut grater machine rental rate of IDR 10,000/hour which has the potential to be rented for 900 hours/year, and the maintenance cost to profit ratio was 10.6% which implies that the coconut grater machine with a capacity of 15 kg/hour is still prospective and feasible to use for the next few years.

Progressive wear on drive belt components, brake lining thickness, double lining bowl and other components of continuously variable transmission (CVT) on 160 cm3 automatic motorcycles are the problems faced. The purpose of component replacement planning is to obtain maintenance costs in 2026 and maintenance to profit ratio. The component replacement planning method includes collecting previous maintenance data, applying the inspection-replace-repair-overhaul (IRRO) method, evaluating component conditions, predicting component lifespan, predicting labor costs, predicting supporting equipment and supporting materials to be used in maintenance, predicting spare part replacement time, predicting maintenance costs in 2026, and calculating the maintenance cost to profit ratio. The results of component replacement planning obtained maintenance costs in 2026 are IDR 8.151.667,- with an estimated rental rate for Automatic Motorcycles of IDR 12,500/hour which has the potential to be rented for 3960 hours/year, and the ratio of maintenance costs to profits is 16.4% which implies that the 160 cm3 Automatic Motorcycle which was first used in 2021 is still prospective to generate profits and is suitable for use in the coming years.

The problem lies in the difficulty of locking the pulley retainer on automatic motorcycle transmissions without using a special Y-shaped key. The purpose of the study is to obtain a special pulley retainer lock product on automatic motorcycle transmissions that can be adjusted the distance between the two retaining pins through adjusting bolts with easy and effective locking steps. The study method includes the design of the pulley retainer lock component formation, the selection of stainless steel pulley retainer lock materials, the production of pulley retainer lock components through flat and curved forging, turning the handle, forming a Y-shaped lever pair plate, drilling 2 holes at the ends of the lever, drilling the Y-shaped auxiliary tool opening and closing pins, and drilling the Y-shaped auxiliary tool opening distance adjustment bolts, assembling the components that form the pulley retainer lock, and testing the use of the pulley retainer lock. The production results are in the form of a special pulley archery key with a total length of 300 mm, the maximum opening distance on the axis of 2 pens is 110 mm, the length of 2 pen tips is 7 mm with a total pen length of 30 mm, and one diameter is 9 mm with a total pen length of 30 mm, the adjusting bolt for the opening angle of the pulley retaining key measures M6x20 mm, and the diameter of the Y-shaped tool rivet pen used is 6 mm.

The problem with the sugarcane press machine is a decrease in performance in sugarcane pressing because it has been used since 2020 with an initial price of IDR 3,000,000, which is predicted to be IDR 5,500,000 in 2025 which occurs in the main components of the roler mill, V-belt, and bearings. The purpose of scheduling replacements and repairs is to obtain a schedule, estimated maintenance costs, and the ratio of replacement and repair costs to the profit of renting a sugarcane press for the period 2026. The scheduling method includes collecting data on the use of the sugarcane press machine, a list of replacements for 5 components for roler mills, V-belts, bearings, gasoline motor tanks, and engine frames from 34 components, component prices, estimated labor costs, equipment costs, supporting material costs, application of the inspection, replace, repair, and overhaul (IRRO) method, scheduling replacements and repairs, and calculating the ratio of replacement costs to profits. The results of the replacement and repair scheduling are in the form of maintenance costs of IDR 958,000, with a rate of IDR 10,000/hour for 588 hours/year, resulting in a profit of IDR 5,880,000, and a ratio of maintenance and repair costs to profit of 0.16%.

Problems in the meatball dough grinder are low production, increasing maintenance costs and disappointed meatball dough customers who receive orders late due to problems with the electric motor, Pulley, V belt, cutting knife. The purpose of the replacement scheduling is to obtain costs, maintenance-repair schedules in the period 2026, and the ratio of maintenance costs to profits. The replacement scheduling method includes collecting previous period maintenance data, applying the inspection-replace-repair-overhaul (IRRO) method, evaluating component working conditions, predicting component life, predicting repairman costs, predicting supporting equipment that will be used in maintenance, predicting the time to replace spare parts or reinstall components after repair, estimating maintenance and repair costs in 2026, and calculating the ratio of maintenance costs to profits. The results of the replacement scheduling show that the maintenance costs in 2026 are IDR 2,530,000 with an estimated rental rate for the meatball dough grinder of IDR 10,000/kg which has the potential to be rented for 1300 hours/year, and the ratio of maintenance costs to profits is 4.9% which implies that the meatball dough grinder with a capacity of 5 kg/hour still has the potential to sell well and is suitable for use in the coming years.

Frequent damage to the grinding disc components and the transmission system of the 15 kg/hour rice flour grinder is a problem faced. The purpose of scheduling component maintenance and repairs is to obtain predictions of maintenance and repair schedules and costs for the period 2026. The component maintenance and repair scheduling method includes examining previous period maintenance and repair data, applying the inspection-replace-repair-overhaul (IRRO) method, assessing component conditions, estimating component life, estimating technician costs, estimating supporting work equipment and supporting materials to be used in maintenance, estimating the time for replacing spare parts or reinstalling components after repair, estimating maintenance and repair costs in 2026, and calculating the maintenance cost to profit ratio. The results of component maintenance and repair scheduling show that the maintenance cost in 2026 is Rp 1,370,000,- with an estimated annual profit potential of Rp 21,600,000, and the maintenance cost to profit ratio is 6.3%, which implies that the 15 kg/hour rice flour grinder is still quite prospective and feasible to use for the next few years.

The problem with previous studies was the use of polyester resin as a matrix in kacang goat hair fiber composites, whereas in the latest study, epoxy resin was used, which has not been widely used. The aim was to obtain the tensile strength of composites that could be used as an alternative material for fan blades. The research method used was experimental with composite fabrication using the hand lay-up method, varying fiber lengths of 10 mm, 20 mm, and 30 mm, and varying immersion times in a 5% NaOH solution for 25, 50, 75, and 100 minutes. Tensile strength testing was carried out using the ASTM D638 standard with a total of 36 specimens. The test results showed that specimens with a fiber length of 30 mm and a soaking time of 50 minutes produced the highest tensile strength of 28.69 MPa, while the lowest tensile strength of 15.38 MPa was obtained in specimens with a fiber length of 10 mm and a soaking time of 100 minutes. This indicates that the highest tensile strength value is 46.37% greater than the lowest value, so the combination of a fiber length of 30 mm and a soaking time of 50 minutes is determined to be the optimal parameter in this study.